Made BitmapFont ctr public (#300)
Made BitmapFont ctr public (#300)

I'm not using the MonoGame content pipeline, so i need the contructor to be public to be able to manually load a BitmapFont from file
rafaelalmeidatk/MonoGame.Extended,HyperionMT/MonoGame.Extended,cra0zy/MonoGame.Extended,Aurioch/MonoGame.Extended,LithiumToast/MonoGame.Extended,rafaelalmeidatk/MonoGame.Extended