UI improvements, avoid CCMU breaking – delete Duchy upgrade area, use build-queue detection in lieu of unit detection

[michaelcrusso]

It would make far more sense to integrate the entire upgrade process directly into the Duchy button menu. This would also allow me to simply write custom tooltips that would provide the player with upgrade costs and bonuses, and provide up-to-date information on the current level of the Duchy's buildings without having to resort to initiating the upgrade process first. No chat space taken up by information, either.

It will be more complicated to write it up this way because of the need to use the Firegraft plugin, and also the unit-production system will have to be replaced by a build-queue detection system using button refresh, but this would represent a significant QOL improvement, as well as prevent the unit limit and "Cannot Create More Units" error from breaking the upgrade triggers, as units can be put into queue even if the map is maxed out.