More scanner cleanup. Renamed bol and eol tokens.
Fixed a bug with alternation parsing

Fixed a bug where alternations with more than two alternatives and  one
of them ending in a group were being incorrectly nested.
Minor code cleanup
Broke expression.rb into seperate class files. Reordered expression object tests.
Moved the expression helpers into a separate file to use from other scripts.
Named groups are capture groups. Removed content format from to_s.
Finally fixed the ambiguity in the regex-based scan of group_options.
Raise an error on quantifiers without a target.
Rakefile cleanup, prep for a new release. Replaced deprecated gempackagetask with the new package_task, cleaned the test tasks, and centralized version info.
Bumped minor version number.
Added stubs for ruby 2.0 syntax.
Not correct *is* wrong.
Delete useless cruft.
Removing expression_helpers after removing the runner and matcher.
Clean up and comment the new scan_options method in the scanner.