Add more markers to source server

[indig0fox]

Marker References: https://github.com/alexcroox/R3-Web/blob/ac92ae0ac3655c051eef5d5685d843bdfc829b95/dist/inc/classes/Replays.php#L298

On my personal clone, I've hardcoded in local site reference, with these placed in /assets/images/markers. It requires an update to the function below to make it return a static array of compatible marker names (see end of desc.).

It also required an update here for the JS player to use the new icons accordingly. https://github.com/alexcroox/R3-Web/blob/ac92ae0ac3655c051eef5d5685d843bdfc829b95/dist/assets/app.js#L1180-L1185 replaced with iconUrl: '/assets/images/markers/' + markerType + '_black.png',

Please update the source site (https://r3icons.titanmods.xyz/) with additional "mil" and "hd" icons, both in JSON reference & with the source image files. Images included in the attached .zip below. This will let anyone still using the server reference expand what editor-placed markers are displayed in the JS player without needing to make the same changes to their source code. markers.zip

public function getObjectiveMarkers() {
		return '[
"ellipse",
"hd_objective",
"hd_marker",
"hd_flag",
"hd_arrow",
"mil_arrow2",
"hd_ambush",
"hd_destroy",
"hd_start",
"hd_end",
"hd_pickup",
"hd_join",
"hd_warning",
"hd_unknown",
"hd_dot",
"mil_box",
"mil_triangle",
"mil_dot",
"mil_objective",
"mil_flag",
"mil_arrow",
"mil_ambush",
"mil_destroy",
"mil_start",
"mil_end",
"mil_pickup",
"mil_join",
"mil_warning",
"mil_unknown"
]'