crecord: refactor hunk edit action to use ui.edit The previous version of this code did a lot of dancing around a temporary edit file that ui.edit already handles.

edit: allow to configure the suffix of the temporary filename Sometimes, we can pick a more appropriate default suffix than ".txt", for example, diffs could have a ".diff" suffix.

merge: save merge part labels for later reuse We permit the caller of merge operations to supply labels for the merge parts ("local", "other", and optionally "base"). These labels are used in conflict markers to reduce confusion; however, the labels were not persistent, so 'hg resolve' would lose the labels. Store the labels in the mergestate.

ui: add prompt argument to write (issue5154) (API) When code like filemerge._iprompt calls ui.prompt, it expects the user to see the output in addition to getting the prompt. Other code such as histedit may call ui.pushbuffer, but its goal is not to interfere with prompts, so this commit adds an optional prompt flag to ui.write and has _readline include that argument. ui.promptchoice calls ui.prompt which calls ui._readline. This commit also updates hgext.color.write.