histedit: import chistedit curses UI from hg-experimental I don't tend to like curses interfaces, but this gets enough use at work that it seems like it's worth bringing into core. This is a minimal import from hg-experimental revision 4c7f33bf5f00, in that I've done the smallest amount of code movement and editing in order to import the functionality. .. feature:: `hg histedit` will now present a curses UI if curses is available and `ui.interface` or `ui.interface.histedit` is set to `curses`. Differential Revision: https://phab.mercurial-scm.org/D5146