Default unknown stage added

Default unknown stage is now a user preference that can be adjusted.
Current default value remains the same (i.e. 7).  Also updated the
loadSTAGES.m file to incorporate different epoch counts between what
the stage file (.STA) has and what the highest value it contains is
(i.e. epoch 700 listed, but only 600 epochs given) and the number
expected from the .EDF.