Add `BlockController::getUniqueIdentifier()`

Add `BlockController::getUniqueIdentifier()`

`BlockController::getIdentifer()` returns the same result for a block
and a clipboard block that contains a reference to that block. This is
awkward for javascript and other things where you need a unique
identifier for a block
Fix Unsanitized Server Variables

Fix unsanitized server variables in `UrlHelper`
Fix Clipboard Block On Collection Version Delete

Fix Clipboard Block On Collection Version Delete

- Check `btCoreScrapbookDisplay` to make sure block is not pasted from
  clipboad elsewhere on site
Fix `PermissionAccess::isPermissionKeyInUse()`

Fix `PermissionAccess::isPermissionKeyInUse()`

Change from `PermissionAccess::isPermissionKeyInUse()` to
`PermissionAccess::isPermissionAccessInUse()` as there is not method
`isPermissionKeyInUse()` in the `PermissionAccess` class

Throws undefined method error in upgrade from 5.5 series
Add ccm-block-field-group div, remove extra div
Close unclosed div in collection_delete
Close unclosed ccm-required-meta div
Add missing quotes to attribute value
Close unclosed fieldset
Open the tbody in users search.php

...it's being only closed...
Remove extra </p> in greek_yogurt/blog_entry
Explicit closing of iframe tags
Propagate area attributes through layouts
Update item_list.php

Fixed addToSearchRequest, wrong parameter name.
Allow Passing string to getAttributeValueObject

Allow passing string to `Collection::getAttributeValueObject()`

This is intended to line up interface more closly with User and File
objects
Merge pull request #1227 from mkly/add_remo_patch_collection_get_attribute_value_object

Allow Passing string to getAttributeValueObject
Merge pull request #1193 from mkly/add_block_controller_get_unique_identifier_method

Add `BlockController::getUniqueIdentifier()`
Merge pull request #1197 from mkly/fix_unsanitized_server_variables

Fix Unsanitized Server Variables
Merge pull request #1198 from mkly/fix_clipboard_block_removal_on_collection_version_delete

Fix Clipboard Block On Collection Version Delete
Merge pull request #1199 from mkly/fix_incorrect_method_in_560_upgrade

Fix `PermissionAccess::isPermissionKeyInUse()`