Shimatta Opengl: Shader Program: Implement compilation and use functions. Compilation from file still missing

include/shimatta-opengl-program.h

@@ -51,7 +51,7 @@ ShimattaOpenglProgram *shimatta_opengl_program_new_from_file(const char *vertex_
  * @param program Shader Program
  * @param error_text Error message from compilation. May be NULL.
  * @param error_text_size Size in bytes of the error_text buffer. May be 0.
- * @return 0 if successful. If Error error text will hold the error
+ * @return 0 if successful. If Error error text will hold the error. 1 is returned if program is already compiled
  */
 int shimatta_opengl_program_compile(ShimattaOpenglProgram *program, char *error_text, size_t error_text_size);