Standard control key combinations - requests

[onqtam]

Its cool that we can go through words with Ctrl+ Left/Right and etc. but perhaps more standard controls like Ctrl+A for selecting everything (and others I can't think of right now) might be a big plus :)

[BalazsJako]

I have added Ctrl-A. I leave this issue open just in case someone comes up with another suggestion. Feel free to suggest any other key combos. I will try to add them.

[crujose]

Honoring io.OptMacOSXBehaviors would be nice to have. https://github.com/ocornut/imgui/blob/20e89201cb12b9b958f8b0dc24e12649f163380d/imgui.h#L1082

Maybe the next level up would be configurable keybinds/actions from the public interface.

[BalazsJako]

Tab/ShiftTab indents/unindents selected text now.