[Added] possiblity to return a value through the callFunctionIfNotNil
function in quest task module.
[Added] error when calling a function that is nil through the
callFunctionIfNotNil function in the quest task module.
[Added] return value in mocks for SpawnMobiles.spawnMobile.
[Changed] getSpawnedMobiles to be an interface function of SpawnMobiles
module.
[Added] Quest encounter module.

Change-Id: I179df33c8a143c2b37fbebae556e0a287a5bc4d6
Merge "[Added] possiblity to return a value through the callFunctionIfNotNil function in quest task module. [Added] error when calling a function that is nil through the callFunctionIfNotNil function in the quest task module. [Added] return value in mocks for SpawnMobiles.spawnMobile. [Changed] getSpawnedMobiles to be an interface function of SpawnMobiles module. [Added] Quest encounter module." into unstable