Make 'fused game checker' check if it's actually a the program it's trying to load, not a directory with the same name (bug #126)

src/scripts/boot.lua

@@ -195,7 +195,7 @@ function love.boot()
 	love.filesystem.init(abs_arg0)
 
 	-- Is this one of those fancy "fused" games?
-	local can_has_game = pcall(love.filesystem.setSource, abs_arg0)
+	local can_has_game = love.filesystem.isFile(abs_arg0) and not love.filesystem.isDirectory(abs_arg0) and pcall(love.filesystem.setSource, abs_arg0)
 
 	if not can_has_game and o.game.set and o.game.arg[1] then
 		local full_source =  love.path.getfull(o.game.arg[1])