Allow ":" as subparameter delimiter in SGR color sequences.

https://bugzilla.gnome.org/show_bug.cgi?id=685759
Fix performance regression with only one active terminal widget.

https://bugzilla.gnome.org/show_bug.cgi?id=721944
emulation: Fix standout handling (typo introduced by true color support)
Version 0.35.1
Post release version bump
widget: Fix off-by-one in allowed palette size.
widget: Don't try to allocate arbitrary amount of memory.
emulation: Refactor color palette handling

https://bugzilla.gnome.org/show_bug.cgi?id=640040
emulation: Add support for OSC 112 (reset cursor color)

https://bugzilla.gnome.org/show_bug.cgi?id=640040
emulation: Add support for OSC 104 (reset colors)

https://bugzilla.gnome.org/show_bug.cgi?id=640040