Strings chapter overhaul

This version does some major changes to the strings chapter (chapter 11). It has been heavily revised and expanded. Some changes are:

• Clearer about how UTF-8 is decoded into runes.
• A section on how to manually decode UTF-8.
• The old "bubble" about null termination has been made into a proper section.
• The section "Deallocating strings mixed with string constants" has been made clearer and more useful by considering a map instead of an array.
• A section on how the phrase "string constant" can be ambiguous.
• The Windows section on UTF-16 has been mostly rewritten and now uses the new cstring16 type.
• Many, many more small changes and edits.

Changes to other chapters

• Chapter 1.5: Typo fix.
• Chapter 2.4: Note about odin run . -keep-executable (new Odin behavior).
• Chapter 3.2: Typo fix abut type inference.
• Chapter 5.3: Clarification about the .(Type) syntax used to check the variant of unions.
• Chapter 7.4: Clarified a sentence.
• Chapter 7.8: Add information about "contextless" requirement for @init and @fini.
• Chapter 10.1.5: Code typo fix.
• Chapter 10.3: Remove unnecessary slice operation.
• Chapter 11.6: Code typo fix.
• Chapter 15.2: Move bubble about bit_set initializers to a more appropriate location.
• Chapter 15.2.2: Typo fix.
• Chapter 15.3: Typo fix.
• ... and several additional small fixes!

Get the latest version by just re-downloading the book from wherever you bought it.

• Chapter 1: Fix broken Discord link
• Chapter 5.1.3: Typo fix
• Chapter 9.7: rand.int_max range clarification
• Chapter 14.3: Improved 'Special_Array' example
• Chapter 23: Typo fix
• Chapter 26.6: Fix broken WebGPU example link
• Appendix D: Fix compilation error

• New section 17.5 called "Breaking cyclic dependencies using callbacks", about how to use callbacks to work around situations where you'd need a cyclic dependency and how to create rudimentary interfaces.
• Chapter 13.1.2: Updated the tracking allocator examples based on recent changes to how the handling of bad frees work.
• A new section 18.6 called "More complicated build setups". A short section about writing bigger custom build scripts.
• A new section 26.10 called "Code generation": It just says what code generation is and links to an example.
• Appendix D: Removed some unnecessary things from the the Raylib + Box2D sample and made it a bit clearer.
• Added an icon to the HTML version, so it's easier to find the tab.
• Chapter 23.3: Made it clearer that you don't need to avoid dynamic literals, but you need to understand that they allocate memory.
• Chapter 6.3: Typo fix
• Chapter 8.1.3: Fix incorrect direction of the vector from_1_to_2
• Chapter 8.1.4: Consistent use of procedure name draw_image instead of sometimes using draw_texture.
• Chapter 12.1: Typo fix
• Chapter 23.1: Minor rephrasing for clarity

I have read the whole book, essentially doing an extra editing pass. I've made a huge amount of changes that make the text clearer. Here are some of the bigger changes:

• Clarification about the size of My_Union in 5.3
• Use the words "member" and "value" when talking about enums. Previously I used "enum value" and "value". The old wording was confusing and ambiguous.
• Renamed chapter 26 to "A few more things..." and edited the content a bit.
• Mention #load in chapter 26
• Mention @rodata in chapter 26
• A section about "Making libraries compile cleanly" in chapter 26
• New section 7.8 (@init and @fini)
• Section 4.3 (Loops) has been improved.
• Section 6.3 (A pointer to a struct) is now more pedagogical.
• Section 10.3 (Custom iterators) has been improved.
• New section 11.5.1 (Deallocating strings that are mixed with string constants)
• Section 12.6 (context.user_ptr and context.user_index) has a new example.
• Fix for illustration in 2.6 having a minor error.
• Move dynamic literals to chapter 23 (Things in Odin to avoid) since they are disabled by default, for a good reason.
• Chapter 18: Nuance about "not needing a build system" and what I actually mean when I say "build system".
• Made a few things in 6.5 clearer
• Fix typos in 5.1.3, 5.2.1, 6.5, 10.2.1 reported by readers (thanks!)
• Added version number to front.
• Fix for YouTube links using wrong "external link" symbol in HTML version.
• Link to CAT & ONION on itch.io (since it comes with Odin code).
• Mention #reverse in "Chapter 4: Some additional basics"

• Regarding automatic passing as immutable references: Changed "sufficiently large" into "larger than 16 bytes". Recently, Odin changed the threshold to always be 16 bytes, regardless of platform.
• Clarified side-bubble in 6.2 regarding how many bits of a pointer that are usually used.
• Make it clearer what is meant by "procedure's stack memory" in 8.1.2.
• Added a comment in 8.1.3 about what "stack allocated array" means and point out that a later chapter will show how to dynamically allocate fixed arrays.
• Fix for EPUB issue where some of the appendices looked weird.
• Minor typo fixes.

• Fix for EPUB issue where some of the appendices looked weird.
• More nuance in 13.1.1 about cleaning up memory allocations at shutdown.
• More nuance in 5.3.5 about using Odin for non-gamedev.
• Clarifications in 3.2 regarding my sloppy use of the word "decimal".
• Fixed level not being a pointer in 13.2 and added some info about why it needs to be a pointer.
• Fixed an error in 8.1.1 where the index 20 was used instead of index 10.
• Additional typo fixes.

• New section on Address Sanitizer in chapter 13.
• Fixed 28 different typos and grammar issues based on a list that PythagoRascal sent me. Thanks!
• Fixed indentation error in bit_set chapter.
• Clarifications about using bit_set versus using a-set-that-is-a-map.
• Section on Small_Array has has been improved for clarity.
• Mentioned that Untyped Floats can be implicitly converted to integers if no truncation happens.
• Clarification about how delete works.
• Added a bubble that mentioned what @static on local variables does.
• Additional typo fixes, some from people on my Discord. Thanks everyone!