The stuff listed in readme, Plus:

Rewrite all the savers/loaders to be a little more friendly.

SHFLI mode (Reasonably Easy, the infrastructure will handle this no prob.)
SHIFLI mode (A little more work, new interlace system required.  Doable.)

ZX Spectrum colors/mode

More Features, Less bugs.  I really can't be fucked writing here, e-mail me
if u wanna know more, esp.  If you wanna code more!!!!!!!!

Stuff that won't happen (at least not by me :):
UFLI (Not suited to this size of editor, 'coz of wired pixel sizing :)

