This adds a check that the pointer passed to
FILESYSTEM_loadFileToMemory() isn't NULL, and if it is, just returns
early in the function, instead of continuing later and producing a
different, slightly-misleading error message.
Previously, it was guarded behind a check for the length, which is... I
guess still perfectly fine behavior, but there's no reason to have a
length check here; FILESYSTEM_freeMemory() uses SDL_free(), which does a
check that the pointer passed is non-NULL (the pointer that is passed
here, despite not being initialized upon declaration, is guaranteed to
be initialized by FILESYSTEM_loadFileToMemory() anyway, so).
Okay, so basically here's the include layout that this game now
consistently uses:
[The "main" header file, if any (e.g. Graphics.h for Graphics.cpp)]
[blank line]
[All system includes, such as tinyxml2/physfs/utfcpp/SDL]
[blank line]
[All project includes, such as Game.h/Entity.h/etc.]
And if applicable, another blank line, and then some special-case
include screwy stuff (take a look at editor.cpp or FileSystemUtils.cpp,
for example, they have ifdefs and defines with their includes).
