Add support for alternating line highlights?

[darrenkenny]

In GUIs and WebUIs it is common for table-like output for have each alternative row highlighted by a different color for odd and even rows, making tabled output more readable, e.g.:

https://www.w3.org/Style/Examples/007/evenodd.en.html

Unfortunately, given that the output is split, and transformed per-line, there is no way to write an RE, or otherwise to handle this in rainbow.

Would it be possible to add support for something like this? Either by making the odd/even something that could be handled in a configuration file, or by supporting it as a suffix/prefix to some options?

Thanks,

Darren.

[nicoulaj]

Related: #2