* Basic spectator functionality.
Added as a separate nation with full visibility.
* Robots not allowed to spectate :(
* Allow multiple human spectators
* Multiple spectators allowed.
Fix crash when max players in map editor.
* At least one active (not spectator) human player needed
* - Invisible tiles vision for spectators.
- Minimum 1 active player (Human or AI) to start the game.
- temporary only 1 spectator in game
* Revert "At least one active (not spectator) human player needed"
This reverts commit d843bebe
* Add all tech to spectators for resource view
* Spectators couldn't be rolled out from "Random" civ
* Spectator is not a MajorCiv.
corrected random pick
* Small refactor
* No diplomacy button for Specators
* Add fixes from yair210 review.
