To further support more markup languages (e.g. Org-mode, AsciiDoc,
reStructuredText), the name 'markdown' is inappropriate.
This is the first step towards more markup language support.
* UpdateIssueUsersByMentions was calling database write operations while
a transaction session was in progress. MailParticipants was failing
silently because of the SQLITE_LOCKED error. Make sure failures in
MailParticipants enter the log, and pass on the transaction context.
issue: let caller pass in database context, and use it
issue_comment: obtain database context to pass to UpdateIssueMentions
issue_comment: log any error from call to MailParticipants
issue_mail: pass on database context to UpdateIssueMentions
* issue: forgot debug statement