0.18.1 - bugfix for saving 32x30 screens

Immediately after the 0.18 release, one user reported back to me there was a problem with saving nametables.  Turns out a flag could be left uninitialized, which may or may not try to force nametables be RLE compressed on saving - which is generally not what you want.

This has now been corrected, so if you experienced the same problem, this update is for you.