[libcommhistory] Fix ContactGroupModel merging when contacts change

Groups in the model would not be merged when contacts were changed,
which broke the grouping when contacts are resolved asynchronously.
[libcommhistory] Remove unnecessary and verbose debug from ContactGroupModel
Merge pull request #27 from special/master

[libcommhistory] Make EventModel::deleteEvent(int id) invokable by QML
Merge pull request #28 from special/contactgroupmodel-fix

Fix ContactGroupModel merging when contacts change
[libcommhistory] Report unresolved contact addresses
[libcommhistory] Fix tests.xml generation
[libcommhistory] Add RecentContactsModel

Contains the most recent event for each contact, ordered in reverse
chronological order.
Merge pull request #29 from matthewvogt/recent-model

Add RecentContactsModel
[libcommhistory] Fix extremely slow groups query with lots of events

The full join on the Events table caused this query to take several
minutes to execute with 5000 events. Using a subquery reduces that to
under 500ms.

There is more room to optimize these queries later.
[libcommhistory] Suppress contacts without the required address type

When selecting recent contacts for IM, we only want contacts that have
IM accounts.
Merge pull request #31 from special/slow-query

[libcommhistory] Fix extremely slow groups query with lots of events
Merge pull request #30 from matthewvogt/suppress

[libcommhistory] Suppress contacts without the required address type
[libcommhistory] Fix Qt4 build