tools: bmp2tiles clearer error message
-rw-r--r-- 14 .gitignore
-rw-r--r-- 677 Makefile
-rw-r--r-- 110 REAMDE.md
drwxr-xr-x - gfx
drwxr-xr-x - inc
-rwxr-xr-x 17200 romheader
drwxr-xr-x - sample
drwxr-xr-x - src
-rw-r--r-- 335 swan.ld
drwxr-xr-x - tools