initial rm_ranges functionality (requires collapsed ranges)
complete rm_range functionality with updates to add_range and collapse_ranges
update range_length and is_in_length to work with new add/rm scheme
add context-sensitive output_ranges function
update method of exporting functions to match Exporter's recommended good practices; add :ALL alias to import all functions
update range tests: add_range, rm_range, is_in_range, range_length, output_ranges, collapse_ranges (all tests pass)
add tests for ranges that include negative numbers
Merge branch 'feature/remove-ranges' into develop
update version info to 0.2.0
Merge branch 'release/0.2.0' into develop