BUG: Drop incorrect & useless query on client libraries info update

This commit fixes following error:

  SQL error in ClientLibrary::Save()():ERROR:  relation
  "client_site2library_id_seq" does not exist
Cosmetics: Simplify some if conditions

Unset variables is a subset of empty variables:

 !isset($var) == true  implies  empty($var) == true
 !empty($var) == true  implies  isset($var) == true

Thus,

 !isset($var) || empty($var)

could be simplified to:

 empty($var)

The patch is generated by:

 find . -type f -name '*.php' -exec sed -i 's/if(!isset($\([^)]*\)) || empty($\1)/if(empty($\1)/' '{}' \;
 find . -type f -name '*.php' -exec sed -i 's/if(empty($\([^)]*\)) || !isset($\1)/if(empty($\1)/' '{}' \;
 find . -type f -name '*.php' -exec sed -i 's/if(isset($\([^)]*\)) && !empty($\1)/if(!empty($\1)/' '{}' \;
 find . -type f -name '*.php' -exec sed -i 's/if(!empty($\([^)]*\)) && isset($\1)/if(!empty($\1)/' '{}' \;
BUG: Fix two typos in file viewer

This commit fixes following errors:

 PHP Notice:  Undefined variable: uploadFile in /var/www/cdash/viewFiles.php on line 65
 PHP Notice:  Trying to get property of non-object in /var/www/cdash/viewFiles.php on line 65
 PHP Notice:  Undefined variable: dbsize in /var/www/cdash/viewFiles.php on line 88
BUG: Fix a typo

This commit fixes the following error:

 PHP Notice:  Undefined variable: coveragestatus in
 /var/www/cdash/ajax/getviewcoverage.php on line 299
ENH: Support PostgreSQL in filter data functions

Tested-by: Nils Gladitz <nilsgladitz@gmail.com>
BUG: Fix undefined variable usage in test viewer.

This commit fixes the following issue:

  PHP Notice:  Undefined variable: extras in /var/www/cdash/viewTest.php on line 273,
  referer: http://localhost/cdash/viewTest.php?buildid=391
BUG: Fix conditional comments in generated html markdown
PEDANTIC: Correctly set 'selected', 'checked' and 'multiple' html attributes
PEDANTIC: Always specify 'type' attribute for <script> tag
PEDANTIC: HTML doesn't allow 'link' tags in the <body>

This fixes tons of errors like "File does not exist: /var/www/favicon.ico,
referer: http://localhost/cdash/createProject.php" in httpd logs.
BUG: Fix minor html markdown issues
BUG: Fix displaying help message for the CTestConfig entry on Edit Project page
ENH: Check that git directory is writeable

and avoid undefined index usage if it's not.
BUG: Fix a minor PostgreSQL incompatibility in test failure graph viewer

This patch fixes the following error:

  PHP Notice:  Undefined index: count(*) in /var/www/cdash/ajax/showtestfailuregraph.php
  on line 74
BUG: Fix undefined variable usage in changes viewer

This commit fixes the following error:

  PHP Notice:  Undefined index: checkindate in /var/www/cdash/viewChanges.php
   on line 355