Stability improvements and better streaming (chromecast mostly)

[pablorusso]

I have done major changes to the play, metadata and restart process.

The code redesign, includes:

• a much better multithreading support
• preventives restart/reconnect to avoid delays when playing
• locks and semaphores to avoid errors when multiple calls are done from different threads.

Benefits:

• I reduced the play lag to almost zero. Time to time, it reconnects and you still see lag, but not often.
• I haven't meet anymore the "cannot cast" screen in chromecast. Further testing still required to be able to say all cases are solved, but works better than before for sure.
• It can stream using DLNA. It has lag, but at least do not give errrors.

[fuzeman]

We use a new streaming method in the develop branch which is a lot more reliable. I'm still planning on having the option of using the old streaming method, but this needs to be re-designed a bit.

After I've got the old streaming method re-implemented onto develop, I'll merge these changes in.

[pablorusso]

I am aware this modifications somehow crash with the streaming method change your are working at (I haven't seen new version, so don't know how big is the impact)

Anyway I am sure the current streaming method works great with this changes. Would be great if everybody using the plugin could benefit of this changes. I have been streaming to chromecast for hours without any cut, error or delay.

Honeslty, I don't how can we include this changes in current master, without breaking your develop branch.

May be you can offer an improved version with this changes until the develop branch is ready? Offering two plugins with different streaming methods so people can pick the one that works better for them? What do you think?

Thanks!