finished off sprite font implimentation like normal sprites

to fix Error 1 Inconsistent accessibility: field type
'System.Collections.Generic.Dictionary<string,Atempt_5.SpriteText>' is
less accessible than field 'Atempt_5.GameWindow.DrawableFont'
C:\Users\rhys\Dropbox\MonoGame2DSpriteGame\Atempt 5\GameWindow.cs 15 47
Atempt 5