Added two failing tests for select/deselect with Space button in multi-select mode:
-Idea is to let space-select ONLY toggle selection for the focused item,  also in
  multi-select mode.
Rewrite tests which used space to test for anchor location - incompatible
  with the proposed space behaviour change
Change toggleSelection to use remove/push instead of writing directly
  to <observableArray> selection, thereby leaving the selection state
  of other items in the array untouched.
This makes the new tests added in commit #cfa91d8 pass