Single header code for parsing INI file data.

Modify as needed. I recommend swapping out integer types for explicitly sized ones.

• Assumes ASCII character codes.
• Same license terms as STB. Available under MIT license or public domain unlicense.
• No preprocessor usage inside ini.h itself. Add an include guard if desired.
• Standard C99. Standalone language only, the standard library is not used.
• Zero heap allocations.
• One additional data type: struct ini_line_info. No usage of typedef.
• Eight static leaf functions.

See test.c for example usage.