Make "default"/empty pattern a parameter.

Allow user to set pattern for unused bits in global register when
calling set_global_register.
Allow tests to run sequentially.

Using del self.chip to reset chip.
Reverse order of bitarray input to global register

Now an input of bitarray("10") will get output first 1, second 0 instead
of the opposite.
Add more tests, refactor global register setup.

Test for DACLD.