handle trailing semicolons

[SingingBush]

just so you're aware, I found a bug in your code: sdlang-dev#1

I raise a PR when fixed

[SingingBush]

I've fixed this in my fork but not done PR as I've changed project structure to maven.

When testing, I'm parsing the following SDL

// Trailing semicolons are optional
title "Some title";

// They can be used to separate multiple nodes
title "Some title"; author "Peter Parker"

besides the semicolon issue I've also noticed that it ends up with 2 Tags for 'title'. Is right that SDL should allow duplicates? I would've expected that it should only be there once so think this may be a bug but couldn't tell as http://sdl.ikayzo.org/display/SDL/Language+Guide doesn't exist any more.