renamed font.c/h to text.c/h
moved compiling of shader files/strings into debug.c
    - null terminate constant shader strings in debug.c
make length unsigned in read_file function
add Color typedef
fix lowercase y
rename font.c/h to text.c/h in Makefile too
add font registry and text render function
    - a registry for registering pointers to fonts, allocated on the
      heap, so that they can be retrieved or deleted with an integer id,
      simple way to avoid dangling pointers
    - as of yet not completed funtion to render text with a specific
      font at arbritrary positions in 3d space
test executable modifications for latest changes