Fixed sm_feature and sm_alias, added sm_maxhealth

Fixed sm_feature, it didn't mark a -1 user id as invalid.
Fixed sm_alias, the server console coudln't use alias commands.
Added sm_maxhealth, to change the maxhealth keyvalue (requested for tf2)
Version 1.4 - Added sm_ksay

Added sm_ksay to send a message to the key hint box.
Fixed sm_respawn for Synergy

Fixed sm_respawn for Synergy