read_bugspec: start off with infinity for x_min and y_min, delete _get_lower
work on docstrings, refactor _all_points_match to be 2.4 compatible
tests.py: add docstring, remove unnecessary newline
bugbuster.py: docstrings, method order, simplifications
bugbuster.py: formatting and docstring changes
rename _reached_row_border to _reached_end_of_row
model.py:minor formatting, docstrings