Added option to customize Pinned folder location

Items can be pinned to directories that require administative privileges
(such as Open-Shell's default installation directory), so long as users
take ownership of the pinned folder. Also adds a command to Open-Shell's
context menu that opens the current pinned folder.

Adds general support for directory-based settings by creating a new
setting type called TYPE_DIRECTORY which uses a new bool added to
BrowseLinkHelper, called bFoldersOnly. START_MENU_PINNED_ROOT
has been removed, and all instances of both it and BrowseLinkHelper
have been adjusted accordingly. To create your own directory-based
settings, use CSetting::TYPE_DIRECTORY. Empty directory paths are
reset to their default value as they can cause unexpected behavior.

Src/Lib/Settings.h

@@ -32,6 +32,7 @@ struct CSetting
 		TYPE_SOUND,
 		TYPE_FONT,
 		TYPE_MULTISTRING,
+		TYPE_DIRECTORY,
 	};
 
 	enum