Added NOMR metric to ast.py

[zaqbez39me]

Added new metric - count of number methods with @Override divided by total number of methods. Here it is namedNumber of Overriding Methods Ratio (NOMR)

Blocked by #316
Closes #192

[zaqbez39me]

@yegor256 please, check this out after #316

[yegor256]

@zaqbez39me what about a unit test? how do we know that this code works as expected?

[zaqbez39me]

@yegor256 tests are implemented in #316

[yegor256]

@zaqbez39me I think, you should also remove the shellcheck disable=SC2317 line

[zaqbez39me]

@yegor256 oops, sorry, forgot to add this change to staged

[zaqbez39me]

@yegor256 check it. Fixed all the issues and enabled tests

[yegor256]

@rultor merge

[rultor]

@rultor merge

@yegor256 OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge

@yegor256 Done! FYI, the full log is here (took me 20min)

[yegor256]

@zaqbez39me thanks!