This makes the FontManager use the default font size of 16 once in __init__ instead of add, and render functions also. This way, the size can be set once on init and not overridden to 16 during render.
The render function will also use the default alias if one is not provided.
Nice, thanks. What do you think about going a step further and making the font size an attribute to the FontManager class? This would allow the user to change it at any time without using the size argument permanently or recreating the whole FontManager object.