Miscellaneous CIV IV bugfixes

Included fixes for:
* Lib/oracle multiple techs
* Trade route turn order bug
* Foreign trade route cities lost permanently when your city using those
routes is destroyed
* Build culture double production
* Build wealth/research/culture + production automation double
production
* Proposed trades including cities, where the cities no longer exist to
be trades, are not cancelled
* Production decay counter on a type of build (e.g. axeman) is not reset
after completing one if the next item in the queue is of the same type
* Feature growth/disappearance rates, and bonus discovery (mine pop)
rates, do not scale with game speed