SpawnListEntry Configured to read and save optional parameters
LivingHandler and SpawnList optional can be chained together by prefixing either or both with the AND '&' symbol.
Spawn parent tag now considers the operands '&' or '|' as valid prefixes.
Setup SpawnList optional with valid property keys
Tweak parsing property tag failure message to better indicate which parent tag is failing
Merge branch 'feature/spawnListOptionals' into dev0.9 Closes #30