Rewrite log parsing in Mercurial and fix whitespace bugs on the way:

- tags and branches with spaces are now properly parsed (issue 663)
- use --style instead of --template option of hg to include much more
  output for the log command; use that to query the parent revisions of
  a revision (if any) and also to query the actual changes of a revision
- make the log parser much more robust towards changes in the "header"
  of the log output

NEWS.mdtext

@@ -2,10 +2,13 @@
 
 ## New Features
 
+- Mercurial source views now show parent revisions (if any) and detailed change information
+
 ## Bugfixes 
 
 - monotone zip archive entries now all carry the revision date as mtime (issue 645)
 - Timeline only displays filter options for items a user has actually access to (issue 655)
+- The log, tags and branches parsers for Mercurial are more robust now (issue 663) 
 - Fix the self-link of the RSS feed (issue 666)
 - Fix SSH public key parsing issues and improve the check for existing, uploaded keys (issue 679)