Added readme for creating tests.
Found and fixed interesting bugs in destroy_db when there is no world.
renamed the testfile to testrunner to make it clear it is actually running the texts. Also, made testrunner more focused on the actual running of the tests.
Added debug target to test makefile.
Main method extracted to separate file to make it easier to test the _rest_ of the code.
munit is added as a submodule by running `cd src; git submodule add https://github.com/nemequ/munit.git` .
Unit testing has so far only been tested on ubuntu.