Render: Bitmap fonts

[eprikazchikov]

Is your feature request related to a problem? Please describe.

As UI designer I would like to have an ability to selects fronts rendering mode.
Currently Thunder Engine supports only SDF fonts which works good with big glyphs.
For small sizes I would prefer to use bitmap fonts.

Describe the solution you'd like

• Add support of bitmaps glyphs in Font class
• Add support of it in Label and TextRender