Add option to check changed lines rather than whole files

Problem/Motivation

When fixing a few lines in a file, the check fails if there are coding standards violations anywhere in the file. It should not be necessary to fix an entire file to make a small change.

Steps to reproduce

Change a line without coding standards violations in a file which has coding standards violations on other lines.

Proposed resolution

Use coverageChecker to check only changed lines if it is available.