Moved session_destroy() to functions.php
Removed session_start() from default.class to start.php
Added new debug_info() function for information about memory handling, etc
 - can be enabled/disabled using the DEBUG constant
 - can/will be expanded with more information
 - not related to Convrtr->Debug (which is intended more for local testing)
Cleaned up some errors for php error logs (mostly some undefined vars)
Consolidated navigation to make room for more features
Adjusted some language entries
Fixed error handling in check.php: specifically with large files
 - .htacess to adjust post and upload file limits
 - new uploadError()  function to catch file upload errors and return the appropriate response
 - see comments in check.php for workarounds on files larger than allowed limits
Fixed incorrect download for url_encoded data