Add join to the accepted tags

Added the ability to join other tables. Needed this to join wp_postmeta to filter pods according to meta...
Properly load Pods_Templates

Did this ever work?  Maybe I'm missing something here
Ensure the files are actually included

Not exactly sure why this was only showing its face with xcache on and working (?) normally without
Remove class check, the next file included does the same check

This allows Pods_Templates to work if pods-frontier is also loaded
Remove check of class loaded

Could wrap the whole class loading block in an else if necessary, but I don't think it is
Add 'pre_select' hook to select

Seems like a filter here could go a long way for future expandability
#2477: initial commit of Pods data function tests
Switch to apply_filters and change name
Update qTip2 version for #2487
Change Pods usage of qtip script name, use jquery-qtip2 and update version string for #2487
Merge branch '2.x' into feature/2487
Merge pull request #2492 from pods-framework/feature/2487

Update qTip2 to 2.2 and fix handle usage
Merge pull request #2478 from pods-framework/feature/2477-add-data-tests

#2477: initial commit of Pods data function tests
Merge pull request #2450 from jamesgol/preselect

Add 'pre_select' hook to select
Merge pull request #2437 from jamesgol/templatesload

Properly load Pods_Templates
Merge pull request #2335 from humancopy/2.x

Add join to the accepted tags
Merge branch '2.x' into feature/2.x-optimizations

Conflicts:
	includes/general.php