Safely construct filename in OutputToH5

Use os.path.join instead of manual construction.
This fixes Issue #13.
Check result of getcwd calls

This is safer and prevents compiler warnings.
Ignore compiled python libraries (*.pyc) in git
Copy unmodified WaveformAtAPoint code from Triton

Source is Triton:5e1a6911cb08b3fe1e99e004614f0a3553bdac08.
Update WaveformAtAPoint for GWFrames compatibility
Improve WaveformAtAPointFT::Match SWIG interface

Parameters passed to Match as in/out must be explicitly cast
to doubles in swig, since python's types are float, numpy.float64, etc.
Interpolate.cpp: Fix gcc compiler warning

Put parentheses around ambiguous order-of-operation comparisons.