RAYMATH_EXTERN_INLINE was renamed to RAYMATH_HEADER_ONLY, which user code
may define if they want to use it as header-only library. If multiple
files in the same project define RAYMATH_HEADER_ONLY, they might each
have duplicate out-of-line definitions of the same functions.
By default, raymath.h exposes inline definitions, which instructs the
compiler _not_ to generate out-of-line definitons, if out-of-line
definitions are required, those of the file defined with
RAYLIB_IMPLEMENTATION are used instead. There may be only one such file.
In C++ mode, the compiler will select only one out-of-line definition
automatically, so no need to define a RAYLIB_IMPLEMENTATION.
Unfortunately, we have to remove raymath function declaration from
raylib.h as those declarations would lead to duplicate out-of-line
definitions which would yield linker errors. This problem didn't
exist with GNU89 or C++, because there multiple defintions are ok,
but in C99 they aren't.
Otherwise we may run into LoadDefaultFont and crash in rlLoadTexture
Also moves InitTimer() before InitGraphicsDevice(), to allow it to be
tested even if InitWindow ultimately fails.
In case graphic device could not be created it returns false instead of
failing with an error tracelog (and consequently closing the program).
Window initialization success could be checked with new function
IsWindowReady()
You can't do much with raylib if glfwInit or glfwCreateWindow fails,
currently it just exits by means of TraceLog(LOG_ERROR.
User code, however, might want to fall back to a text-only UI
or display a warning if raylib can't be used.
glfwSetWindowPos was called on a NULL window, triggering an assert
inside GLFW. Check for failure and exit cleanly by means of
TraceLog(LOG_ERROR instead.
OpenAL Soft backend is still available in audio module, I'm thinking if
exposing it for building in some way or just left it there for advance
users to switch to it manually in case of necessity...
Feature macros need to be defined before #including any headers,
preferably through the build system, but this is good enough.
Fixes a compile error on my fork's Travis CI.
