GSLHelpers: add brackets around 'name' where needed
LatticeTiling: ensure consistent length is used for bounds data
LatticeTiling: check that bound has not already been set
LatticeTiling: fix bugs in XLALMetricEllipseBoundingBox()

- Correct normalisation
- Return the full extent of the bounding box, i.e. multiply by 2
LatticeTiling: rename XLALGet...() functions to just XLAL...()
SuperSkyMetrics: improve fitting for large reference time offsets

- where fitting becomes rank deficient
- more closely mirrors the Octave implementation
SuperSkyMetrics: check for negative eigenvalues