GCC 10 defaults to -fno-common resulting into errors about a multiple
definitions of variables that where defined instead of declared by
a mistake in a header file that is included into more compilations
units.

These files were erroneusly dropped when adding the manual pages.

libgcrypt does not know MD5 on RHEL 8 and thus the test failed. This
patch recognizes IE_NOTSUP error and skip the test in that case.

If a printf() argument formatted with "%s" can be NULL, GCC 9.2.1 emits
a format-overflow warning. This patc fixes the affected tests.

Code style adjustements.
Check fir curl_easy_escape() and strtol() failure.
Document testing MEP credentials.
Document authorship.

After upgrading GnuTLS to 3.6.4,
test/simline/certificate_user_password_authentication tests that exhibit
a missing client's certificate and a bad client's certificate started to
fail. That's because cURL returns a network error instead of a TLS error in
that case when TLSv1.3 is used.

This patch work arounds this cURL deficiency.

See a similar GnuTLS bug report
<https://gitlab.com/gnutls/gnutls/issues/615>.

Some distributions started to remove en_US.UTF-8 from their build
infrastructure and use C.UTF-8 instead.

This patch actually tries using C.UTF-8.

To test a conversion to a UTF-8 locale, we need to have a UTF-8 locale
supported by the standard library. We tried en_US.UTF-8 that is widely
available and then cs_CZ.UTF-8. However, some distributions started to
remove en_US.UTF-8 from their build infrastructure and use C.UTF-8
instead.

This patch skips the inapplicable tests.

This patch extends testing library to allow skipping tests.

A new SKIP_TEST(reason) macro can be used to exit a test function because
a current test cannot proceed for outer reasons.

A new SKIP_TESTS(number, reason) macro can be used to skip a number
of tests. The skipped tests must not be invoked by a program control
flow. SUM_TEST() still must be called at the end of the unit. This is
different from ABORT_UNIT() that reports a unit failure.

Memory has been leaked when calling with NULL raw_sender_type parameter.

The entry dmAttachmentSize has not been freed. Moved free(dmType) to a
location which corresponds with the definition of struct isds_envelope.

It's funny there is still no official documentation despite the testing
instance implements these changes because latest available Provozní řád
is from 2017-03-05.

The changes were announced only in a short extraordinary change
advisory.