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.