Changing charlooks doesn't work

[rmkaplan]

Describe the bug
@nbriggs reported and @fghalasz confirmed that changing the charlooks through the menu or programmatically doesn't work in some situations, although it was working for me when my INIT file was loaded but not if it was not.

Turns out that my INIT set the TEDIT.DEFAULT.PROPS to (FONT (CLASSIC 10)) instead of the default to NIL. When I removed that, it failed even when the rest of my init was loaded.

The reason was a mishandling of the fontclass DEFAULTFONT when not other FONT was specified. Fixed in #1857