Lots of Clipboard interaction fixes.

V1.6.16.3
Improved the clipboard handling. If the clipboard data is damaged or incorrect then Atari Font Maker will try to fix as much of the data as it can.
If for example the clipboard only contains characters, and no font data, then you will not be able to paste into the font window. If on the other hand only font data is present then you can only paste into the font window and not the view window.
If data fields are too short then it should not cause problems, since the values are replaced with sane defaults. Missing characters are shown as ? in the preview window.