change LircClient to inherit & use QThread instead of pthreads

[keith@…]

According to the coding standards, Qt should be used for non-gui tasks, and code should be platform-independent. This patch is small and accomplishes the following:

1. The LircClient class is changed to inherit from QThread (as well as QObject). The Process() method is basically renamed to run().
2. The unused member pth is removed from LircClient.
3. Static function SpawnLirc is removed from libs/libmythui/mythmainwindow.cpp and much of its body is moved to where the thread is started.
4. A LircClient object is created on the heap. On a failure in LircClient::Init, it was not deleted. This is fixed.
5. A few minor changes in variable names etc. that help readability.

This patch really changes no functionality. With the exception of the PTHREAD_CREATE_DETACHED flag, everything will work the same as before. This also paves the way for more interesting changes in the LircClient, like being able to restart the client without restarting the frontend.

[danielk]

Discussed in mailing list. The thread's detached property is important, we don't want to leak threads.