CommandPanelMaxButtonX and CommandPanelMaxButtonY game.cfg options

Add two new config strings that control the maximum amount of rows and columns the Command Panel can utilize for techs, units and abilities.

Currently as of AoMEX, the maximum amount of rows that can be used are 3, with the maximum amount of columns being 8. Without uimain.xml modding, the standard amount of columns and rows shown are 3x7, though the engine can support an additional column at the moment with modding.