#314 Mob/Encounter locking

when you are attacked be a Spawn, the Spawn is automatically locking the encounter

encounters should only lock once the player has attacked back

also it should be player option as to whether encounters lock at all

ALT-O Group Options Default Group Auto Lock Default Solo Auto Lock

adding "can attack a locked encounter outside of group" to this issue to close Issue #426

starting the road down this issue thought I would add if we don't initially set the spawn "locked_no_loot" field in the visual struct to ENCOUNTER_STATE_AVAILABLE (1) it will not accept any other encounter states. Initially sending the spawn with locked_no_loot = 0 seems to disable that (so you likely would have to do an initial send of STATE_AVAILABLE before any other flags, if that were to happen).

I just put AVAILABLE as our default state in the Spawn::Spawn constructor

Issue #504 will focus on the group options and those encounter settings in there. For now this will get the base logic in for solo/group encounter locks.