Break lalsupport into smaller translation units to speed up build

This is a demonstration of a technique to speed up the build of lal by breaking some very large source files into smaller translation units. The lalsupport library contains several source files that repeatedly expand macros to generate type-specialized versions of functions. This is a severe bottleneck in the build because these large files are built as single translation units.

This change, if applied throughout lalsupport, would dramatically speed up build times with make -j.