GSLHelpers.h: print GSL error message in case of failure
LatticeTiling: go back to using functions to define parameter-space bounds

- Simpler to implement and more flexible
- Lower and upper bounds are now calculated separately using separate bounds
  data; compare lower and upper bounds data to see whether dimension is tiled
- As in commit d7dfdc5f693a0fb33975a0520c076fd15f3ab437, CFSv2 square grids
  (gridType=8) are unmodified, but age-braking indices (9) return slightly
  different points due to different numerical order of bound computations.
  So we disable checking the gridType=9 results for now.
- Also remove XLALSetLatticeEllipticalBounds().
- Also various other minor cleanups.