Merge pull request #44 from special/master

[declarative] Add contactUpdated and contactRemoved signals to ContactAddressLookup
[libcommhistory] Adapt to changes in libcontacts for sort/display order
Merge pull request #45 from matthewvogt/sort-property

[libcommhistory] Adapt to changes in libcontacts for sort/display order
Update dependency version for contactcache
[libcommhistory] Improve handling of multi-target groups
[libcommhistory] Never combine multi-target groups in ContactGroup
Don't add empty remote UIDs to groups from event updates

Remote UIDs may be empty for events sent to multiple targets that have
no specific destination.
Merge pull request #46 from special/multitarget

Improve support for groups with multiple targets
[libcommhistory] Fix exporting and behavior of ClassZeroSMSModel

Class zero events have no ID, so the eventModel logic would ignore all
events after the first one.
[libcommhistory] Improve ClassZeroSMSModel API and export to declarative

The deleteEvent function was not useful, as class zero messages have no
ID (since they are never stored). A clear function was added instead to
clear the model.

Also added a newMessage signal for more convenient usage, especially
from QML.