Created some tests for contains and overlap operations to check DE-9IM compliance

[3Davydov]

No description provided.

[esabol]

Thank you for this, @3Davydov ! I love more tests.

There's already a "contains_ops" and a "contains_ops_compat" files for testing. I wonder if it would be appropriate to put your "contains" tests in one of those files?

[3Davydov]

Hello, @esabol !
I think it's still worth making a separate file for this. The tests in the "contains_ops" and "contains_ops_compat" files are relevant only for the current logic.
If it is decided to switch to the DE-9IM model, then it will be necessary first of all to focus on the tests from "contains", and it may be more convenient to work with a separate file.

[vitcpp]

@esabol I propose to accept this PR with some trivial changes. Tests do not affect functionality but can be used to learn semantics of operations. I have some ideas how to improve and reorganise it. @3Davydov did a nice analysis of existing algorithms and found that they are not fully compliant with the semantics of operations on figures as described in the DE-9IM model (and OSG Simple Feature Specification). I understand that we can not just change the behaviour of operations to make it compliant but we can update the docs with some notes about differences with reference models.