api function to select external clock added

Better not to use because the clock selection is not yet stable from FW
side.
PixTestPattern-new parameters: input file name

testParameters updated.
API CHANGE: merge the two probe dictionaries into one for convenience.
Select either analog or digital signals via PROBE_ANALOG / PROBE_DIGITAL.
Bump version to 1.4.3
Merge branch 'master' into cython_manual_interface

Conflicts:
	core/api/api.cc