HDMI Tx and Rx cores along with tests

[srivatsan-ramesh]

@tenthousandfailures, @cfelton, @jck, @josyb, @dargor0

The PR contains HDMI Tx and Rx cores. Xilinx application notes xapp460 and xapp495 were used as reference.

It has two test files one for checking the cores' functionality and the other for checking whether the cores are convertible.

• test_hdmi_core.py
• test_core_conversion.py

The documentation for the project can be found here.

[coveralls]

Coverage increased (+1.8%) to 92.212% when pulling 5880b8c on dev into 307af90 on master.