[mythtv-cmyth] Enabling Internal EDL

When internal EDL is activated then configure and plug EdlStreamHandler to the playback.

- Add setting g_iEdlMethodType  to choose the method (PVR | Internal)
- Add global g_bEdlEnbaled to switch On/Off EDL functionality with menu hook
- Add Menu hook menuHookSwitchOnOffEdl
- Add notifications about EDL status