Doxygen documentation for text.h, SFont.h, setup.h, realpath.h, readline.h, palette.h, keyboard.h, io.h, input.h, hotkeys.h, helpfile.h, errors.h; and a basic description for all other headers.

Removed 2 unused function prototypes (They escaped translation)
In each C file, added a #include of its own header, to help doxygen generate a more complete documentation for the C files (and also double-check function prototypes)

All these changes don't change the generated executable, it's still beta 99.0.

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@752 416bcca6-2ee7-4201-b75f-2eb2f807beb1

pxdouble.c

@@ -27,6 +27,7 @@
 #include "global.h"
 #include "sdlscreen.h"
 #include "misc.h"
+#include "pxdouble.h"
 #include "pxwide.h" // for Display_transparent_line_on_screen_wide()
 
 #define ZOOMX 2