added impl for hal::SetClockSource() in DUMMY hal

- required change since new function was added w/ commit 0d2498f8ae7fa6a3ba0729059c1b2c5f17970b99
- fixes linking errors when using dummy hal
made use of probe dictionary in cython wrapper

- added probe and reg dictionaries in separate pxd files to avoid namespace conflicts w/ getinstance() methods
added probe dict in python cmd line util