fortran .mod files

[François-Xavier Coudert]

> We don't have formal tests for the .mod compatibility, but since 4.3.0 a
> MD5 number is saved in the .mod file and thus one needs to actively
> change the MD5 number if an incompatible change occurred. (Though some
> changes might get undetected as the module-test module file in the
> test suite does not use all features.)

I'll simply add that the test is only designed to check that the MD5
sum is correctly calculated on all platforms. (Even more specifically,
I feared that CRLF systems might surprise us, but I was wrong).

FX