This closes issue #23

A small missing '$' caused a lot of mischief. Augmented also the tests
to detect something like this in the future

Now they just cluttered the main build directory, put them also in
private_modules/. This of course assumes that no two test programs
define modules with the same name.

Also, this necessitates that the shared sources are also only compiled
once, thus I put them into an internal libtool convenience library and
link all test programs with it.

Remove all references to private functions and symbols from the public
Fortran modules. Install also only the public modules

This allows to install several versions of the library in the same
directory

If compiled with MPI, the necessary "mpiexec -n 2" was not written
in the check scripts. This commit is based on a patch provided by
Michael Banck from debian.org

In principle we don't want any stop statements in the library, but for now its
better to abort with an error than to abort successfully

For programs with lots of files with very long names it could happend
that the shell commands assembled by make failed with E2BIG. By
inserting some newlines into the commands we can mitigate this for now.

A general solution would probably only be to save the argument one at a
time into a file and read this file from fortran_dependencies.pl

For programs with lots of files with very long names it could happend
that the shell commands assembled by make failed with E2BIG. By
inserting some newlines into the commands we can mitigate this for now.

A general solution would probably only be to save the argument one at a
time into a file and read this file from fortran_dependencies.pl

The optional build via "--enable-assumed-size-arrays" is also
tested in the CI

Using Fortran assumed size arrays makes debugging a lot harder,
thus as default these are not used in ELPA.
However, it might be, that some compilers make unwanted copies
if calling subroutines with array slices. Then switching back
to assumed size arrays might create a performance gain

Now they just cluttered the main build directory, put them also in
private_modules/. This of course assumes that no two test programs
define modules with the same name.

Also, this necessitates that the shared sources are also only compiled
once, thus I put them into an internal libtool convenience library and
link all test programs with it.

Remove all references to private functions and symbols from the public
Fortran modules. Install also only the public modules