[Charmap] various fixes

The patch attached resolves following issues:

• Skip rotated font (font name starting with "@" char)
• Fix a comment (misspelled "Richedit")
• Fix enlarged preview font in font name is long (it truncated font name in 31 chars when copying)
• Fix 2 magic values (255 here is not meaningful, and it doesn't even entirely showing Unicode Plane 0)