dirstate: improve error message on file/directory clash

imerge extension and test

Merge with stable

merge: do early copy to deal with issue636 Without copies/renames, merges source names are 1:1 with their targets. Copies and renames introduce the possibility that there will be two merges with the same input but different output. By doing the copy to the destination name before the merge, the actual merge becomes 1:1 again, and no source is the input to two different merges. - add a preliminary scan to applyupdates to do copies - for the merge action, pass the old name (for finding ancestors) and the new name (for input to the merge) to filemerge - eliminate the old post-merge copy - lookup file contents from new name in filemerge - pass new name to external merge helper - report merge failure at new name - add a test

localrepository: allow rawcommit to commit with an empty message

Update style of record's cmdtable to match mercurial/commands.py

os.isatty isn't available on Windows, so use sys.stdin.isatty()

convert: add config option to turn off use of branch names

Add record extension, giving darcs-like interactive hunk picking

ui: get readline and prompt to behave better depending on interactivity