When an email notification concerns a specific object (issue, note,
merge request, etc.), add a link to the footer of the email that opens
the item's page in a web browser.
Rationale:
* The link is predictable: always the same text, always at the same
location, like any reliable tool.
* It allows to remove the inline-title in many emails, and leave only
the actual content of the message.
There was some funny syntax in merge request email templates. There was a ! before
the merge request number when there probably should be a #. This may be some carry over
from markdown but should not be in email templates. There were also some capitalization
discrepancies among the subject lines. For those OCD people out there I standardized the
capitalization. :)