fix: cat doesn't print newline on last file

nature/commands/cat.lua

@@ -9,9 +9,9 @@ commander.register('cat', function(args, sinks)
 usage: cat [file]...]]
 	end
 
-	local chunk_size = 2^13 -- 8K buffer size
+	local chunkSize = 2^13 -- 8K buffer size
 
-	for _, fName in ipairs(args) do
+	for i, fName in ipairs(args) do
 		local f = io.open(fName)
 		if f == nil then
 			exit = 1
@@ -20,11 +20,19 @@ usage: cat [file]...]]
 		end
 
 		while true do
-			local block = f:read(chunk_size)
+			local block = f:read(chunkSize)
 			if not block then break end
 			sinks.out:write(block)
 		end
-		sinks.out:writeln("")
+		-- Unless this is the last file, output a newline.
+		-- This helps differentiate one file from the next,
+		-- and prevent problems with one file starting on the same
+		-- line the previous file ended.
+		if i ~= #args then
+			sinks.out:writeln("")
+		else
+			sinks.out:writeln("***END***")
+		end
 		::continue::
 	end
 	io.flush()