This adds optional MouseFlags that can be used to adjust what is
tracked for mouse reporting (leaving the other modes to be handled
by the terminal.) This should work on all XTerm style terminals,
but on Windows we have no way to be selective here.
This replaces high numbered function keys on xterm style
emulators with modifiers. So pressing SHIFT-ALT-F1 is
reported as exactly that, for example. This also extends
that to the insert, delete, home, end, etc.
There is a chance that this will break some emulators --
of particular concern are older VTE based emulators and
rxvt (and derivatives). However, we think that most VTE
derivatives are now much more closely aligned to xterm.
The Wyse50 alternate character set was changed (likely
due to a bug fix in ncurses).
Implemented key kombination of Shift + PgUp/PgDn for Gnome terminal.
Same combination copied to all other terminal implementations which use same
codes for Shift + Up/Down but since this is tested on Ubuntu 16.04 with Gnome
Terminal 3.18.3 it could be that it is not correctly implemented for some of the
other terminals.
Garrett D'Amore