Several improvements (#9)

* fix icon filename

* update pp2d to fix preview problem

* several improvements:
- rely on a single header for simple/common headers
- cleaned up main by putting the interface drawing function in its own file
- load previews from .zip themes (may cause some loading times when launching
- only need 1 shuffle image thanks to pp2d's blending abilities

* not needed anymore

* fix preview color and position

* forgot

* add proper icon loading
thanks steveice10 for bannertool which this was pretty much taken from

* only add proper themes to the list

* add slightly more space between the icon and the name

* not monospace, the little movement every blink is annoying

* fix typo

include/fs.h

@@ -27,7 +27,7 @@
 #ifndef FS_H
 #define FS_H
 
-#include <3ds.h>
+#include "common.h"
 
 FS_Archive ArchiveSD;
 FS_Archive ArchiveHomeExt;
@@ -35,9 +35,10 @@ FS_Archive ArchiveThemeExt;
 
 Result open_archives(void);
 Result close_archives(void);
-int get_number_entries(char*);
+
 u64 file_to_buf(FS_Path path, FS_Archive archive, char** buf);
 u32 zip_file_to_buf(char *file_name, u16 *zip_path, char **buf);
+
 u32 buf_to_file(u32 size, char *path, FS_Archive archive, char *buf);
 void remake_file(char *path, FS_Archive archive, u32 size);