TLCO fix & boot file extension change

This commit fixes the TLCO boot option (which hasn't been working for a
while now), and also changes boot file extensions from .boot to .lua.

sys/boot/tlco.lua

@@ -0,0 +1,30 @@
+local run = os.run
+local shutdown = os.shutdown
+
+local args = {...} -- keep the args so that they can be passed to opus.lua
+
+os.run = function() 
+	os.run = run
+end
+
+os.shutdown = function()
+	os.shutdown = shutdown
+
+	_ENV.multishell = nil -- prevent sys/apps/shell.lua erroring for odd reasons
+
+	local success, err = pcall(function()
+		run(_ENV, 'sys/boot/opus.lua', table.unpack(args))
+	end)
+	term.redirect(term.native())
+	if success then
+		print("Opus OS abruptly stopped.")
+	else
+		printError("Opus OS errored.")
+		printError(err)
+	end
+	print("Press any key to continue.")
+	os.pullEvent("key")
+	shutdown()
+end
+
+shell.exit()