Medical Treatment: Add graves event and setting for markers

[BrettMayson]

When merged this pull request will:

• Adds Create Grave Markers setting
• Adds ace_placedInGrave that fires regardless of marker creation
• ace_placedInBodybag will not fire if marker creation is disabled

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[LinkIsGrim]

I'm not sure if grave "markers" is a good name: I had to look to see if you weren't referring to map markers.

Code looks good.