This PR makes windows builds a bit more flexible and reliable, in preparation for putting out a conda package for pyscamp.
There are some backwards incompatible changes made:
pyscamp requires cmake 3.15 or greater now (up from 3.12). Most users should have a much more recent version of cmake anyway so this shouldn't be too big an issue.
Some changes were made to how to specify environment variables to set compilers/generators for SCAMP and pyscamp, overall this should be more aligned with the normal usage of cmake.
This PR makes windows builds a bit more flexible and reliable, in preparation for putting out a conda package for pyscamp.
There are some backwards incompatible changes made: