Add stealth mobs

Add new roamflag stealth to hidden the name and get untargetable (like
chigoe) to mobs.
SQL: fixed Tiamat's Absolute Terror being AoE
CORE: fixed status effect icons for IDs over 512 and higher
Database corrected wrong pos for a groundstome in the boyahda tree
Merge pull request #391 from santssoft/master

Add stealth mobs