Attempt to allow empty lines in telex/files.

These were previously filtered out. Unfortunately now there's some
awkward emtpy lines in various places, but, I prefer having empty
lines show since that makes typing much simpler.

mods/terminal/init.lua

@@ -76,9 +76,11 @@ local function make_formspec(output, prompt)
 		"textlist[0.4,0.5;11,6;output;"
 
 	local c = 1
-	for part in output:gmatch("[^\r\n]+") do
-		f = f .. minetest.formspec_escape(part) .. ","
-		c = c + 1
+	if output then
+		for part in output:gmatch("([^\r\n]*)\n?") do
+			f = f .. minetest.formspec_escape(part) .. ","
+			c = c + 1
+		end
 	end
 	f = f .. minetest.formspec_escape(prompt) .. ";" .. c .. ";false]"
 
@@ -565,7 +567,7 @@ local terminal_use = function(pos, node, clicker, itemstack, pointed_thing)
 	end
 	-- send formspec to player
 	fsc.show(name,
-		make_formspec("", "> "),
+		make_formspec(nil, "> "),
 		context,
 		term.recv)
 	minetest.sound_play("terminal_power_on", {pos = pos})