corrected and documented binary-timing equations in XLALAddBinaryTimes()

  - added extensive doxygen  documentation of the derivation and
    final expressions that are implemented in the code
  - passes previously-failing test-cases with eccentricity>0
  - also fixed up old LALGetBinarytimes() in BinarySSBTimesTest, in order
    to make that test pass [and still do something useful for future refactoring
    optimization of XLALAddBinaryTimes()]
  - fixes #1074, #1142, #1043
new test script testCFSv2_binary.sh for testing CFSv2 on binary signals

   - injects a binary signal, runs PredictFstat and a targeted CFSv2 search,
     and compares the two to within tolerance (5%)
   - refs #1074, #1142