Added fields to set per-survey email subjects to the email invite, remind, confirm and register email messages. Modified various files to allow setting and use of these fields. Added translations to english administration language file. Will add these lines to other languages shortly. Also modified register.php and tokens.php to use $thissurvey variable from getSurveyInfo() function. IMPORTANT NOTE: You need to run the checkfields.php after getting this update to create the new fields in the surveys table.

git-svn-id: file:///Users/Shitiz/Downloads/lssvn/trunk/unstable@1262 b72ed6b6-b9f8-46b5-92b4-906544132732