Moved some interrupt enable/disable and interrupt handling

Moved some interrupt enable/disable and interrupt handling
stuff from client drivers into ni_tio.c.
ni_stc.h:
	Added some stuff for correlated digital output waveforms
	that I missed in earlier commit.
ni_660x.c:
	Added beginnings of support for buffered input counting (untested,
	definitely doesn't work yet due to empty interrupt handler).
	Added INSN_CONFIG_SET/GET_ROUTING support,
	to allow switching of output signals between
	counter outputs and static digital output.  Fixed channel mix-ups
	on input/output selection for static dio.  Fixed static digital
	output to work on full 32 bits.  Replaced some preprocessor macros
	with inline functions.