Added Bing Hybrid Map
Added Open Street Map
Set map selection menu checks (exclusive check)
Handle proper image type otherwise disk caching fails

As this is no longer google specific, renamed everything google to qgc.

Although the method is marked as thread safe in the docs, if you use a
database plugin it ends up not being thread safe.

Operator = is not thread-safe, but copy constructor looks to be. This
is causing an intermittent crash.

QSerialPort buffering too slow on Windows.

Need to check for QImage failure otherwise it will through a qWarning.

Found by valgrind.