A test to run ulfius on FreeBASIC

It uses ulfius with a few modifications to be able to run websockets without the need for (porting) gnutls to FB, as the porting would require a lot of headers.

(It still uses gnutls internally for hashing and other minor stuff).

It also required a few minimal modifications to fbfrog.

• Dockerfile.base builds the base docker image;
• ulfius-install.sh builds ulfius from the custom source, disabling GNUTLS, CURL and the client tools. It installs to /opt/ulfius to later copy to a new docker stage;
• fbfrog-install.sh builds fbfrog from the custom source;
• fbfrog-runner.sh runs the fbfrog commands to /opt/ulfius, to later be copied to another stage;
• *.fbfrog fbfrog options;

• test.bas a minimal test that shows the integration with ulfius, with JSON and websockets+JSON;
• Dockerfile builds the test image, assumes base image is basic-ulfius;

There are some current limitations on running FreeBASIC as a Linux daemon, namely not being able to use pause and instead having to use the FB's sleep (wait for user input), which requires the container to be run as interactive (-ti).

There is also (apparently) no stderr, or at least not with the conventional numbers and not exposed to the FB's "api". It's probably possible to use with the standard C libraries.