API: Add information about author or type of slot for markPanels created by CombinedArms slot

[Scarletta]

When a player is in a CombinedArms slot like GameMaster, TacCommander, JTAC, the markPanel.author property is empty.

The .initiator property of the associated events (S_EVENT_MARK_ADDED, S_EVENT_MARK_CHANGE) is also empty when creating or editing a markPanel.

Adding a value like playerID or type of slot (GM, TacCom, JTAC) to these properties would help MP server hosts to build map marker command restrictions.