Parse new colors for highlight and shader

[ChenghaoMou]

This should address #38.

• added color parsing in both line_to_stream and line_from_stream;
• added color map for hard-coded highlight and shader colors;
• added test function and test file for all colors;

Waiting for #39 #41 #42 so some of the tests can be properly run.

[ricklupton]

Thanks @ChenghaoMou -- now that #39, #41 and #42 are merged, from a quick look it looks like one failing test now passes but there are still 2 more failing -- is that something you can check / look into?

[ChenghaoMou]

@ricklupton Thanks for the reminder. There was an issue in line_to_stream, but now it's fixed.

[felurx]

@ricklupton Is there anything holding this back from being merged?