App Bridge +get_reservation +modify_reservation

Added the 2 functions described (should test).  get_reservation may need
to be changed if we go to XML.  Commented out include algorithm.php,
it's not in use and it's generating junk text right now.  Added
commenting.  Removed a comment in the pagr_db.php file.
App Bridge +get_item

get_item now works.  Also changed all references of isset() to empty()
because empty() is a more universal indicator of whether an item is set
than isset().
merge