Added Texture class
Remove unused stuff form TextRenderer.h
Texture: Add Getter for texhanlde and Setter for aspect ratio
TextLabel: Switch to Texture class
TextRenderer: Use Texture class, Remove Text2TextureFixedSize
NumberLabel: Switch to Texture class

This brings better kerning for free since every texture has its own UV coords.

I used an array of textures instead of vector to avoid the ctor of texture getting called too often/at start of prog.
Added ImageWindow to display pics!
Marked TODO in TextRenderer