TODO

# TODO

## Lexer/Preprocessor

[ ] Lex c23
    - Missing unicode/wide chars and strings
[x] Change to using lexer structs instead of global variables.
    - This allows easier lexing of `#define` and `#include`
[x] Implement `#error`, `#warning`, and `#pragma`
[x] Implement `#define` and `#undef`
[ ] Implement `#include` and `#embed`
[ ] Implement `#ifdef`, `#ifndef`, `#elifdef`, `#elifndef`, `#else`, and `#endif`
[ ] Implement `#if`, `__has_include`, `__has_embed`, `__has_c_attribute`
[ ] Implement `#`, `##`, `__VA_ARGs__`, `__VA_OPT__`
[ ] Add predefined macros (see [cpp-reference](https://en.cppreference.com/w/c/preprocessor/replace#Predefined_macros))