Start to work on interface compilation

[K-Phoen]

Hey!

Type: bug fix & new feature

This pull request affects the following components:

• [ ] Core
• [ ] Analyzer
• [x] Compiler
• [ ] Control Flow Graph
• [ ] Documentation

In raising this pull request, I confirm the following:

• [x] I have read and understood the Contributing Guidelines?
• [x] I have checked that another pull request for this purpose does not exist.
• [x] I wrote some tests for this PR.

Small description of change:

Start supporting interfaces. This is a WIP and more commits will follow (I'll probably begin with tests)

[ddmler]

before merge can you add interface testcase to missing docblock analyzer? since it needs your compile event to work i have commented that out.

[ovr]

ping @K-Phoen

[K-Phoen]

Sorry but I won't have time to work on this, you can close the PR or finish it :)