added CMake configuration for tests
added tests for coding and decoding tag ids'
Extracted a tag drawer from creator and tested it

This in-memory tag drawer will be used for integration tests.
removed superfluous test files

It is not so useful to have a separate file just to declare the main method
when there is only one source file for the tests. It is still possible to
do so, though.
added a minimal integration test
moved tag_info_t out of the interface
Moved params to generate chilitags' bitmatrices

...into the default values of Codec's Constructor
added integration tests on real data
Shortly documented how to run the tests

This includes the address of the test-data repository and examples of commands
for a make-based build.
Merge pull request #9 from qbonnard/tests

Adding automated tests