Fixes and cleanups to hgeditor:
- "HG: merge resolve" isn't supported for a long time now.
- detection of unchanged commit message if signing is turned off.
- don't add manifest hash to commit message if not signing.
<item>
<title>#desc|firstline|escape#</title>
<link>#url#?cmd=changeset;node=#node#</link>
<description>#desc|escape|addbreaks#</description>
<author>#author|obfuscate#</author>
<pubDate>#date|rfc822date#</pubDate>
</item>