This commit fixes#1969 by adding support for matching a window's type
against _NET_WM_WINDOW_TYPE_NOTIFICATION. The userguide and tests were
updated to reflect this change.
* Implement criterion specs just like it is done in the spec for the config
* Declare variables in test case early so the 'my' keyword can be dropped in the actual test cases
A container selected with criteria should be moved with the `move
[direction]` command, instead of this command always acting on the
focused container.
