Added Support for new append method of NZBGet 13+
Fix for symlinking during Post-Processing

As described here: https://sickrage.tv/forums/forum/help-support/bug-issue-reports/5016-several-issues
Provider searches for backlog, manual, and failed have been re-worked to not hammer the providers so much plus perform alot faster.
Fixes for a few provider issues plus passing of search_mode variable.
Provider results get sorted by quality before filtering occures.
Places Quality UNKNOWN items from provider results at end of itemsList leaving order of sorted items highest to lowest.
Merge pull request #651 from Supremicus/nightly

Change SQL in templates.
Merge pull request #650 from dhellwich/patch-1

Fix for symlinking during Post-Processing
Merge pull request #649 from Prinz23/nzbget13_append

Added Support for new append method of NZBGet 13+
Fix proper searches with ABD and sports
Tidy PP log message
Fix for extensions being stripped off by mistake made when adding in -RP fix from few commits ago.
Moved code for marking failed download successful out of loop.

Newznab providers now create season search strings for all searches as single ep search strings combined with using rage id numbers seems broken currently.
Fix for validating episode data during provider result gathering.
Quality sorting fixed for provider results.

Reverted newznab search strings being confined to just season till we can find a better way of correcting the issue with Usenet Crawler.
Merge pull request #652 from adam111316/fix_airdate_propers

Fix proper searches with ABD and sports
Merge pull request #653 from adam111316/clearer_PP_logs

Tidy PP log message
Fix for sports shows.
Added code to perform disposal of bs4 class when finished as well as perform garbage collection afterwards, this fixed a memory leak issue SR was experiancing during backlog/manual/failed searches.
Further improved memory handling of bs4 for torrent providers.