Module file support

[ppenzin]

Second part of the module support - emitting and consuming module files.

It is probably possible to keep Fort's module files compatible with GNU Fortran. I don't have a definition for the format yet, besides it being a gzipped text file:

$ cat test.f90 
module test
  integer x
end module
$ gfortran -fsyntax-only test.f90 
$ cp test.mod test_mod.txt.gz
$ gunzip tes_modt.txt.gz 
$ cat test_mod.txt 
GFORTRAN module version '14' created from test.f90
(() () () () () () () () () () () () () () () () () () () () () () () ()
() () ())

()

()

()

()

()

(2 'test' 'test' '' 1 ((MODULE UNKNOWN-INTENT UNKNOWN-PROC UNKNOWN
UNKNOWN 0 0) () (UNKNOWN 0 0 0 0 UNKNOWN ()) 0 0 () () 0 () () 0 0)
3 'x' 'test' '' 1 ((VARIABLE UNKNOWN-INTENT UNKNOWN-PROC UNKNOWN UNKNOWN
0 0) () (INTEGER 4 0 0 0 INTEGER ()) 0 0 () () 0 () () 0 0)
)

('test' 0 2 'x' 0 3)