Doesn't handle file extensions

[xDShot]

If func_instance entity has parameter pointed into vmf file without .vmf at end, it fails to insert.

For example, it doesn't work:

entity
{
	"id" "9"
	"classname" "func_instance"
	"angles" "0 0 0"
	"file" "instances/kasbah/kasbah_visuals"
	"fixup_style" "0"
	"origin" "1486.92 2133.41 -1.33851"
	editor
	{
		"color" "220 30 220"
		"visgroupshown" "1"
		"visgroupautoshown" "1"
		"logicalpos" "[0 0]"
	}
}

This one works:

entity
{
	"id" "9"
	"classname" "func_instance"
	"angles" "0 0 0"
	"file" "instances/kasbah/kasbah_visuals.vmf"
	"fixup_style" "0"
	"origin" "1486.92 2133.41 -1.33851"
	editor
	{
		"color" "220 30 220"
		"visgroupshown" "1"
		"visgroupautoshown" "1"
		"logicalpos" "[0 0]"
	}
}