[Bookmarks] LocationCompleter now works

BookmarkItem: Added counting of bookmark's visits
[Bookmarks] Various smaller changes

BookmarksTreeView: Select & ensure visibility of newly added bookmark
BookmarksTools: Added function to open folder in tabs
LocationCompleterModel: Removed bookmarks bits in createQuery
QupZilla: loadAddress now opens new tab if current tab is pinned
[Bookmarks] Implement searching in BookmarksTreeView
[Bookmarks] Draw separators in BookmarksTreeView
[LocationCompleterModel] Simplify createQuery function

It is no longer needed to search for bookmarks in database
[Bookmarks] Activate bookmarks with single click in Sidebar
[Bookmarks] Load default bookmarks on error
[Bookmarks] Bookmarks Toolbar is now working