[PATCH] Remove player argument from GUIInterface calls

[elexis]

The new observermode #3168 has added a viewedPlayer argument to a good number of GUIInteface calls. It were cleaner to remove the player and let the caller function pass it explicitly, so those functions would have only one argument (which is an object in case multiple arguments need to be passed).

[elexis]

Default to the viewed player in the GUIInterface to avoid passing the viewed player separately in some places, refs #3168.

Makes the clearing of the cache in selectViewPlayer of session.js actually relevant. Thereby fixes a fog-of-war selection relict when changing the perspective as described in #3850. This was trivial following r18201. Also removes some unused player arguments.

[elexis]

In 18283:

GUIInterface / observermode cleanup as recommended by leper, fixes #3999.

Default to the viewed player in the GUIInterface to avoid passing that separately in some places, refs #3168.
Thus GetEntityState will be called for the viewed player instead of observer playerID, therefore
fixes a fog-of-war selection relict when changing the perspective, refs #3850.
Also remove some unused player arguments.