Introducing filesystem.h

File system has its own header
Introducing system.h

Sys_ prototypes are in his own header
Introducing system.h

Sys_ prototypes are in his own header
Introducing filesystem.h

File system has its own header
Merge branch 'system' of github.com:alericoveri/hecatomb into system
system headers full implementation and cleanup

System function declarations are far more organized now
Formal declarations and cleanup
Merge branch 'filesystem' of github.com:alericoveri/hecatomb into filesystem

Conflicts:
	src/include/filesystem.h
Merge branch 'system' into prereqs

Conflicts:
	src/backends/generic/qgl.c
	src/backends/unix/system.c
	src/common/clientserver.c
	src/common/filesystem.c
	src/common/misc.c
	src/refresh/r_misc.c
	src/server/sv_main.c