uhd: Amends 2fd13c0c, LO lock checks need to be removed from source as well as sink
blocks: throttle resets the timer state when the topblock starts each block, including during a lock/unlock restart.

Addresses issue #649.
docs: Adds a brief explanation about adding and getting items tags inside/outside calls to work.

Addresses issue #699.
blocks: switching last calls from boost::thread to gr::thread.

There are a few places where the threads are specifically used by boost::thread calls in the namespace. If we ever move away from using boost's threads, we might have some more specific cleanup to do, but it's not obvious how to easily abstract this further.

Addresses Issue # 706.
Merge remote-tracking branch 'mbant/uhd/even_less_checks'