Even though VT100-like devices can display non-ASCII characters, they do
not use an 8-bit character set. Special escape sequences allow the VT100
to switch character maps. The special graphics character set stores the
box drawing characters, starting at 0x60, ending at 0x7e. This means
we now pass the character map tests in vttest, even the save/restore
cursor test, combined with character maps. dialog(1) also works a lot
better now.
This commit also includes some other minor fixes:
- Default to 24 lines in teken_demo when using xterm emulation.
- Make white foreground and background work in teken_demo.
4873b07e2a