LALSimulation: ignore test/PNCoefficients
SWIG: do not rename a symbol if re-name would start with a digit or _

- Symbol names starting with a digit are not allowed in Python,
  and names starting with a _ also do not seem to work with modules
- Test by importing LAL_C_SI and LAL_180_PI constants
ihope extended background codes: whitespace and formatting
extended background: fixing application of vetoes

Also tweaking the storage of single triggers to make the
Nitz tricks with dicts unnecessary
pylal extended bg-est: simplify code and print diagnostics
pylal extended bg est : remove zerolag from slide coincs!

also clean up inline comments
Revert get_mchirp_bins in extened_background_utils.py so that it
looks in all mass bins.