Fix to the issues with stray units

diff --git a/PerfectRaid.lua b/PerfectRaid.lua
index 63c51f3..4178f00 100644
--- a/PerfectRaid.lua
+++ b/PerfectRaid.lua
@@ -73,6 +73,7 @@ function PerfectRaid:Enable()
 	self:RegisterEvent("UNIT_MAXRAGE", "UNIT_MAXMANA")
 	self:RegisterEvent("UNIT_MAXENERGY", "UNIT_MAXMANA")
 	self:RegisterEvent("UNIT_MAXFOCUS", "UNIT_MAXMANA")
+	self:RegisterEvent("CHAT_MSG_SYSTEM")

 	--TODO: Make this so we can actually instantiate frames as the users wants
 	for i=1,8 do
@@ -181,6 +182,17 @@ function PerfectRaid:GetColoredName(unit)
 	return string.format("|cFF%02x%02x%02x%s|r", color.r*255, color.g*255, color.b*255, UnitName(unit) or "Unknown")
 end

+function PerfectRaid:CHAT_MSG_SYSTEM(event, msg)
+	if msg == ERR_RAID_YOU_LEFT then
+		for unit,tbl in pairs(frames) do
+			for frame in pairs(tbl) do
+				frame.unit = nil
+				frame.name = nil
+			end
+		end
+	end
+end
+
 function PerfectRaid:UNIT_HEALTH(event, unit)
 	if not frames[unit] then return end
 	local health = UnitHealth(unit)
@@ -355,6 +367,13 @@ end

 local function OnAttributeChanged(frame, name, value)
 	if name ~= "unit" then return end
+
+	for unit,tbl in pairs(frames) do
+		if tbl[frame] and frame:GetAttribute("unit") ~= unit then
+			tbl[frame] = nil
+		end
+	end
+
 	if not frame.unit then
 		frame.unit = value
 	else
@@ -363,12 +382,6 @@ local function OnAttributeChanged(frame, name, value)
 		end
 	end

-	for unit,tbl in pairs(frames) do
-		if tbl[frame] and frame:GetAttribute("unit") ~= unit then
-			tbl[frame] = nil
-		end
-	end
-
 	local parent = frame:GetParent()
 	if value == nil then
 		local num = parent:GetNumChildren()
diff --git a/PerfectRaid.toc b/PerfectRaid.toc
index e8458e2..da8e6e5 100644
--- a/PerfectRaid.toc
+++ b/PerfectRaid.toc
@@ -7,6 +7,7 @@

 Dongle.lua
 DongleUtils.lua
+LockdownLine.lua

 Localization.enUS.lua
 Localization.frFR.lua