Switch to libarchive and camera autodetect between splashes and themes (#142)

* switch to libarchive and get rid of minizip, introduce zip_memory_to_buf

* automatically detect whether the downloaded zip is a splash or a theme

* slightly simpler way

include/fs.h

@@ -37,6 +37,7 @@ Result open_archives(void);
 Result close_archives(void);
 
 u32 file_to_buf(FS_Path path, FS_Archive archive, char** buf);
+u32 zip_memory_to_buf(char *file_name, void * zip_memory, size_t zip_size, char ** buf);
 u32 zip_file_to_buf(char *file_name, u16 *zip_path, char **buf);
 
 Result buf_to_file(u32 size, char *path, FS_Archive archive, char *buf);