Fortran: check for undeclared variables by forcing implicit none everywhere
C/C++: check for unused parameters and return types
removed unused variables from test cases
ci: do missing return and unused arg check with Github Actions
This test currently assumes that the fortran compiler is gfotran, and
if we're not using g++ it skips. This patch changes it to skip if the
fotran compiler and the c++ compiler aren't the same family. This still
may skip in some cases it shouldn't (clang and gfort probably work fine
on windows), but it does enable ifort + ICL. Which is hte point.
Michael Hirsch, Ph.D