Add a mission objectives GUI panel
Add end game dialog
Make necessary changes to existing maps
Remove inconsistencies w.r.t the Surrender order

* Surrendering is now possible even in maps that do not use
  ConquestVictoryConditions.
* The Surrender button is greyed out instead of hidden when it cannot be
  used.
Add some Media functions to new Lua API
Convert gdi01 to new Lua
Added upgrade rule for maps using StrategicVictoryConditions (KotH)