Useful macros and trace logging output for C

Headers:
	- macros.h - Useful preprocessor defines. A lot use GNU extensions. Include this after all other includes to not poison any other headers.
	- ints.h - Uniform naming convention for integer types: i8, u8, i16, u64 ... and for floats: f32, f64, etc.
	- types.h - Includes ints.h and also 128-bit vector shim types
	- trace.h - setting up and managing the logging level. call `trace_init()` to load form env-var, or `trace_init_with()` to set the level explicitly.