Add bracketed paste mode
This patch enables bracketed paste mode (
http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#Bracketed%20Paste%20Mode
).
It's mainly useful for text editors to disable line wrapping and auto
indentation when text is being pasted, rather than typed from keyboard.
On the emulator side, it is supported by at least xterm, urxvt,
gnome-terminal, putty, iterm2; and I have a patch for konsole.
On the application side, vim can be configured easily to handle this, and
I have pending patches for mcedit and joe. Probably many others also
support it.
