Adds system preferences to template context

It's now possible to use
  $gimme->getSystemPreference(preferenceName, defaultValue)
in the templates. For preference names the machine names should be
used. The default value will be returned if the preferences it not
set.
Merge pull request #899 from m038/CS-5584

Adds system preferences to template context
CS-4766 Fix several issues with translation of support settings
TW-47: Fixes issue with not working getCaption method and property on images
Merge pull request #904 from m038/TW-47

TW-47: Fixes issue with not working getCaption method and property on im...
CS-5558 Fix Italian translation of TinyMCE
CS-5558 Update Italian plugins for TinyMCE
CS-5558 Fix campsiteattachment plugin translations
CS-5558 Fix codehighlighting plugin translations
CS-5558 Fix campsiteimage plugin translations
CS-5558 Fix iframe plugin translations
CS-5558 Fix textbox plugin translations and remove unused translations
CS-5558 Add missing translations for campsiteinternallink plugin
CS-5558 Remove unused translations for codehighlighting and iframe plugins
Merge pull request #906 from danielhjames/CS-4766

CS-4766 Fix several issues with translation of support settings
CS-5587 Fix format of legacy translation files
CS-5587 Add English placeholders for missing translation files
Add again missing author route
CS-5495 Fix typo in 'Accout Name'
CS-5495 Fix typos in 'Error occured' etc