Add support for numerical burst injections in SimBurstTables

The existing implementation of the SimBurstTable code does not allow for the injection of numerical relativity waveforms. This is a desirable feature for e.g. supernova and ADI waveforms. This branch implements such support in a way analogous to in a SimInspiralTable, and allows xml files with these columns to be read.

I'm very open to suggestions for better ways to handle this; this seemed like a good, quick solution a couple of years ago when I was preparing the O1 MDC for the burst group, but I'm prepared to make changes to minke (the burst MDC package) to allow for an alternative implementation if that seems more sensible.

Making this change to glue doesn't really make sense until support is added to LALSuite either.