add show_id to TVEpisode

[simonc56]

follow dece4d0

Actually, to get the show of a TVEpisode we only have show name (self.show) which is not reliable because some shows have the same name.
The show trakt id is more reliable than show name because it is unique. This PR adds show_id attribute to TVEpisode.

Example : Top Boy and Top Boy 2019
A TVEpisode from Top Boy 2019 uses slug top-boy (made from slugify(self.show) ) instead of top-boy-2019 to fetch data from trakt api. Therefore data received is wrong.

[glensc]

Released with 3.4.9

[glensc]

The initializer for TVEpisode.show_id was not added.

[glensc]

yet adding it as def __init__(self, show, season, number=-1, show_id=None, **kwargs): triggers this._get rather this._build:

• Add show_id property initializer to TVEpisode #23