Added the mechanism to be able to add a second personal skill, and moved Pursuit Critical, Safeguard, and Return to the second slot.
The generic personal skills, such as Pursuit Critical, were implemented before I started giving everyone unique skills, so they now seem a bit disappointing in their lack of individuality. This change will allow units with these skills to have other skills attached to them.
In addition, units that had a high Pursuit Critical Coefficient in the original but could not be attached to Pursuit Critical in order to have other skills can now be attached. For example, Olwen now has Pursuit Critical in addition to Steady Stance she previously had.
