[Azoth] Added ISupportLastActivity for #1656.
[Azoth Xoox] Added PendingLastActivityRequest for #1656.
[Azoth Xoox] Expose LastActivityManager.
[Azoth Xoox] Code style fixes.
[Azoth Xoox] Implemented ISupportLastActivity for #1656.
[Azoth MuC] Added /last stubs for #1656.

Handling servers and contexts still needs to be implemented.