Simplified gwpy.utils.lal module for lal>=6.14.0
This PR removes support for lal < 6.14.0 by simplifying the gwpy.utils.lal
module. 6.14.0 was released in 2015, so is probably new enough.
Additionally this PR provides a few new methods to simplify mapping python types to LAL type strings (e.g. float
-> 'REAL8'
).
Finally, I added tests of the functions in gwpy.utils.lal
.