PlayerAttachment to deal with multiple capitals.

The Value is the minumum number of capitols that must be held in order to be able to produce.


<option name="retainCapitalProduceNumber" value="2"/>

It is similar to retainCapitalNumber, but only affect gaining income and producing units (probably should be less than or equal to retainCapitalNumber)

If a player has no playerAttachment, then it defaults to 1 (ie: you keep collecting and producing units so long as you control at least 1 capital)