Scanline menu for PCE Fast (courtesy of Ariok)

Overscan cropping is now possible and adjustable via core options. 
Some fixes in frame buffer size.
Change of aspect ratio from 4/3 to 6/5 to be in line with Mednafen (Pce Fast "aspect" mode).
Non-working aspect ratio menu is disabled, use retroarch video option instead.
Revert change to PCE Fast display starting point.

Unneeded with the new Overscan menu.
Allow higher vertical viewport for PCE Fast.

Overscan menu can now display 242 lines vertically.
Merge pull request #53 from Tatsuya79/master

(PCE Fast) Overscan  config menu