Fix: Build infrastructure: Iteration through ary of tests
Added simple insertion test for linkedlist type
Added test for deletion
Added test for inserting/deleting multiple values
Added test for element allocation
Added test for allocating ll_element with data
Fix: Version compatible function calls

As this bullshitbuntu on the CI has only an ancient version of the check
framework in the repos, and a setup with something from the backports
seems to be more difficult than it should be, this patch fixes the tests
here to use only calls to asserts which are present in the check-version
on the CI servers.
Enable verbosity when running tests
Merge pull request #58 from matthiasbeyer/add-ll_tests

[WIP] Add testing for linked list implementation