parsebundletype: add a comment for future generation

bundle: extend the format of --type to support version and compression We had some basic undocumented support for uncompressed bundle2 support. We now have an official extensible syntax to specify both format type and compression (eg: bzip2-v2). In practice, this changeset introduce the 'v1' and 'v2' identifier to make it possible to combine format and compression. The default format is still 'v1'. We'll care about picking 'v1' or 'v2' in regard with general delta in the next changesets.

hgweb: fix border-radius for standards-based browsers While here, remove an old gecko-specific property, as gecko has supported the unprefixed version for many years.

filemerge: move precheck to before files are written out This is much simpler, and also avoids unnecessary disk IO.

filemerge: move 'merging' output to before file creation This has no visible impact but makes some future work simpler.

filemerge.filemerge: make a tuple containing merge paths on disk We're going to need this same tuple elsewhere.

filemerge: switch trymerge boolean to mergetype enum trymerge = False becomes mergetype = nomerge, and trymerge = True becomes mergetype = fullmerge or mergeonly, depending on whether a premerge happens.