xterm extensions

[migueldeicaza]

Assorted OSC codes supported that we do not support shown by dynamic.pl in xterm/vttest show that we are missing:

• OSC 4
• OSC 10 mostly done, pending options update from Foreground/Backround control #111 - dynamic.sh test
• OSC 11 mostly done, pending options update from Foreground/Backround control #111 - dynamic2.sh test
• OSC 12 change text cursor color
• OSC 13 Change mouse foreground/background colours
• OSC 14 Change mouse foreground/background colours
• OSC 17 Change highlight background/foreground colours
• OSC 18 Change highlight background/foreground colours
• OSC 19 Change highlight background/foreground colours

query-color.pl OSC 4
query-fonts.pl OSC 50 - from xterm/vttest

• acolors.sh shows OSC resetting the color palette.