Additonal areas of cleanup

[Spuds]

Quick pass through themes and install areas, mostly to reverse !empty and !isset sillyness

[codecov]

Codecov Report

Attention: Patch coverage is 43.41463% with 116 lines in your changes are missing coverage. Please review.

Project coverage is 33.30%. Comparing base (f8b62c0) to head (d68f678).
Report is 1 commits behind head on development.

Files	Patch %	Lines
themes/default/ProfileOptions.template.php	27.77%	39 Missing ⚠️
themes/default/Admin.template.php	17.39%	19 Missing ⚠️
themes/default/GenericMessages.template.php	6.25%	15 Missing ⚠️
themes/default/GenericMenu.template.php	42.85%	8 Missing ⚠️
themes/default/Register.template.php	0.00%	8 Missing ⚠️
themes/default/Xml.template.php	0.00%	8 Missing ⚠️
themes/default/MessageIndex.template.php	42.85%	4 Missing ⚠️
themes/default/Post.template.php	55.55%	4 Missing ⚠️
themes/default/Display.template.php	86.66%	2 Missing ⚠️
themes/default/ManageMembers.template.php	50.00%	2 Missing ⚠️
... and 6 more

Additional details and impacted files

@@                Coverage Diff                @@
##             development    #3762      +/-   ##
=================================================
- Coverage          34.38%   33.30%   -1.08%     
  Complexity         16512    16512              
=================================================
  Files                430      429       -1     
  Lines              84040    83467     -573     
=================================================
- Hits               28893    27800    -1093     
- Misses             55147    55667     +520     

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