Fix playback when OMXPlayer is enabled

[dagwieers]

A lot of users on Raspberry Pi are affected by a playback issue when
OMXPlayer is enabled. On Raspberry Pi OMXPlayer improves playback of
various streams, but it totally breaks Netflix playback.

This fixes reports on #237, #274, #286, #319, #656

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• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
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[dagwieers]

Hmm, it seemed to have worked once, but I cannot reproduce the fix. So I am not sure that this was what actually change behaviour (it could have been that it was still running when I switched OMXPlayer off).

[dagwieers]

The only reliable way to do this is disabling OMXPlayer on playback, and restore the configuration after playback. Disabling before playback is quite easy, but restoring the configuration is not that easy it seems.

[dagwieers]

def get_global_setting(setting):
    json_result = xbmc.executeJSONRPC('{"jsonrpc":"2.0", "method":"Settings.GetSettingValue", "params":{"setting":"%s"}, "id":1}' % setting)
    xbmc.log(msg='get_global_setting: ' + json_result, level=xbmc.LOGNOTICE)
    return json.loads(json_result)['result']['value']


def set_global_setting(setting, value):
    if value is True or value is False:
        json_result = xbmc.executeJSONRPC('{"jsonrpc":"2.0", "method":"Settings.SetSettingValue", "params":{"setting":"%s","value":%s}, "id":2}' % (setting, 'true' if value else 'false'))
    else:
        json_result = xbmc.executeJSONRPC('{"jsonrpc":"2.0", "method":"Settings.SetSettingValue", "params":{"setting":"%s","value":"%s"}, "id":2}' % (setting, value))
    xbmc.log(msg='set_global_setting: ' + json_result, level=xbmc.LOGNOTICE)
    return json.loads(json_result)

And then in before playback:

            omxplayer = get_global_setting('videoplayer.useomxplayer')
            set_global_setting('videoplayer.useomxplayer', False)
            self.play_video(
                video_id=params['video_id'],
                start_offset=params.get('start_offset', -1),
                infoLabels=params.get('infoLabels', {}))
            return True