Refactored import paths for test utility methods across multiple test files to align with a recent package restructure. Enriched 'read_txt_file' functionality in 'file.py' allowing to optionally skip empty lines, enhancing flexibility for various use-cases. Added tests for the new 'read_txt_file' behavior in a new 'test_file.py'. Renamed 'utils.py' in test package to 'test_utils.py' for better differentiation from the util package in the source code.
Adjusted the way colors are applied to detection annotations to allow support for custom color schemes. Modified 'ColorMap' to 'ColorLookup' across multiple files, adding ability to use a color lookup array. This refinement will enable users to assign custom colors to different detection annotations, offering greater flexibility in visual representation of detection data. Updated related tests to reflect these changes.