Standardize C model names

[butler]

The original agreement was that C models would have a python and C file with the same name. In some cases the C file name is kernel which is also reasonable except that not all are so labelled. In fact since some names are already getting very long adding kernel seems to be less of a good idea. Further those are in the minority so the easiest is to change those names back.

More importantly however kernel is used inside many c models now to package the core of the computation outside the Iq and Iqxy functions. Further in cases where that kernel is used by several models it has been pulled out of the C model file altogether and placed in the \lib directory as a kernel.c file

Changing this only requires changing the C file name and changing the name to include within the Python file so in principle could be done later than 4.0 hence not listed as critical