CRAFTERCMS-227: Delete should not be available when a content is locked

When a content is locked, the 'Delete' option is not available neither
in the contextual navigation nor in the "right-click" menu. Also, in
the case of bulk operations, if at least one content is locked within
all selected then the "Delete" option is not available either.
CRAFTERCMS-206: Insert page type and internal name in form window title

Browser tab title should reflect the page type and the internal name.
For new forms, the window title will only have the page type.
Merge remote-tracking branch 'david/master'