Further developing of the formula AI language

by Bartek W for Battle for Wesnoth

Formula AI language is a great tool for scenario designers and campaign developers, that allows them to write special-purpose AIs that can control single units, groups of units that meet some specified criterias, or a whole side. I would like to further develop this language by adding some new features, and then use it to create good and customizable recruit algorithm/library that could be plugged into any AI.