imdb fix to scrape all genres

[at2010]

Description

for imdb.xml in metadata.common.imdb.com
Only up to 3 genres were scraped. and often in alphabetical order which sometimes misses the most relevant genre. This fix scrapes all genres and switches to use the xx-reference.html instead of main

Checklist:

• [x ] My code follows the add-on rules and piracy stance of this project.
• [ x] I have read the CONTRIBUTING document
• [ x] Each add-on submission should be a single commit with using the following style: [plugin.video.foo] v1.0.0

Additional information :

• Submitting your add-on to this specific branch makes it available to any Kodi version equal or higher than the branch name with the applicable Kodi dependencies limits.
• add-on development wiki page.
• Kodi pydocs provide information about the Python API
• PEP8 codingstyle which is considered best practice but not mandatory.
• This add-on repository has automated code guideline check which could help you improve your coding. You can find the results of these check at Codacy. You can create your own account as well to continuously monitor your python coding before submitting to repo.
• Development questions can be asked in the add-on development section on the Kodi forum.

[KarellenX]

@olympia I think this one is for you.