GitLab

	Added context menu support in smerge mode.
	Most of the part is written by Stefan Monnier.

	* smerge-mode.el (smerge-context-menu-map, smerge-context-menu): New
	keyman and menu.
	(smerge-text-properties): New function.
	(smerge-remove-props): New function.
	(smerge-popup-context-menu): New function.
	(smerge-resolve): Call `smerge-remove-props'.
	(smerge-keep-base, smerge-keep-other, smerge-keep-mine):
	Ditto.
	(smerge-keep-current): Ditto.
	(smerge-kill-current): New function.
	(smerge-match-conflict): Detect the file as `a same-diff conflict'
	if the filename is "ANCESTOR". Put text properties.