Send to options working more sensibly

Changes have been made to the tree in View->Preferences->Mantid->Send To
so that it opperates more sensibly, in specific:
Checkboxes in the tree now switch visibility in the menu on or off.
the "visible" option in the edit dialog has been removed in favor of using
the tree checkboxes.
selection to edit is now made by selecting the item rather then clicking
the checkbox.
functionality of ConfigDialog::createCheckedTreeItem now makes sence based
on the parameters, passing true as the second paramter will now produce a
checked item. This will have broken some other functions that use, it, but
it'll only require that i negate their current value they pass.

Refs #4495
Multi-select functionality restored

The ability to select multiple programs (used for deletion) has been restored

Refs #4495
Nagated affected function calles

My edit to createCheckedTreeItem meant that i had to nagate the second
parameter to restore functionality to normal prior to the change

Refs #4495
Merge branch 'bugfix/4495_SendTo_Program_Checkbox_fix' into develop