Add & Call "Set Slaves in HWI.vi" in PulseBlaster

Continuing Slave Digital channel implementation by adding a Set Slaves in
HWI VI to the PulseBlaster interface and calling it early in Finalize.  As
a master device this means it will get called after all other devices have
had a chance to populate the private data.

It must get called first to ensure all lines have the correct output data
_BEFORE_ expansion by the rest of Finalize HWI.

Works by first flattening all slave channel requests into a single binary
number to be ORed with the extant VLIW output data.  Then it loops over
all VLIW instructions and uses the stored ramp info to determine which
mask to OR with each VLIW line.

Untested, will be making and removing dummy class to test in the near-term
future.