merge: allow smarter tool configuration
Add [merge-tool] hgrc section with:
<tool>.executable = name or path (<tool>)
<tool>.args = args with $local/base/other/output ($local $base $other)
<tool>.priority = priority (default 0)
<tool>.binary = handles binary (False)
<tool>.symlink = handles symlinks (False)
<tool>.checkconflict = check for conflict markers (False)
<tool>.premerge = try internal simplemerge (True if not binary or symlink)
Four built-in tools: internal:{merge,local,other,fail}
Add [merge-patterns] section of the form:
<pattern> = <tool>
Priority of settings is:
HGMERGE
merge-patterns
ui:merge
merge-tools by priority
hgmerge, if it can be found
Changes:
unsuccessful merges leave .orig files
workingfilectx.date = (1000, 0)