underBruhat -- obtain Weyl group elements less than an element for the Bruhat order

Ways to use underBruhat :

• underBruhat(BasicList) -- Weyl group elements just under the ones in the list for the Bruhat order
• underBruhat(WeylGroupElement) -- Weyl group elements just under a given one for the Bruhat order

For the programmer

The object underBruhat is a method function.