Do Not ignore "Link Category" if links in use

I have a clients using the built in link category taxonomy quite frequently so the proposed change will check if there are links before deciding to ignore this particular taxonomy.
Don't always return array on previously looked up fields
Don't always return array on previously looked up fields

The problem was that on a second call to field() $this->row[ $params->name ] is populated,
so $value is set from that and the whole big next block that sets $single isn't called.

Fixes #2347
Fixed #2166
Merge branch 'singlefields' of github.com:jamesgol/pods into singlefields
Get rid of some unnecessary logic
Allow fields to be sorted by orderby …

Two separate but connected issues.  First if orderby is passed then the $data array is
never populated.  Then looping through $ids will always give it results sorted by priority
in the relationships field (data returned by lookup_related_items)

Fixes #2277
Add missed brace
Change the default of display_errors to true

A previous changed corrected the reversed logic that was used in display_error.  This should keep the previously expected
behavior the same
Fix icon in readme

#2359
Allow save_post_meta to delete single meta elements instead of update

At that stage in the code we don't know if there are multiple values in the DB, so the best course of action is to just deal with it like there are multiple elements.

Fixes #2213
Handle user/comment multi simple meta issues
Merge pull request #2350 from jamesgol/orderbyfield

Allow fields to be sorted by orderby & fix #2277
Merge pull request #2348 from jamesgol/singlefields

Don't always return array on previously looked up fields
Merge pull request #2299 from mgratch/patch-1

Do Not ignore "Link Category" if links in use
Merge pull request #2358 from jamesgol/defaultdisplayerrors

Change the default of display_errors to true
fix #825
Increase version to 2.4.4-alpha
Merge pull request #2363 from jamesgol/simplemulti

Allow save_post_meta to delete single meta elements instead of update
add pods_audio() and pods_video() functions #2373
up/admin/view.php expects the global $obj to be set to the Pods_UI object