Update and fixes!

Updates:

New keyboard shortcuts for:

Tools:

• Q - Smooth draw, better for drawing tablet.
• W - Pencil dot, better for precise pixel and corrections.
• E - Shortcut for eraser.

Layers:

• A - For Main layer
• S - For Temporary Layer
• D - To mix Temporary Layer ABOVE Main

Canvas limits guide:

• Z - Disable
• X - 32x32 Canvas
• C - 64x64 Canvas

Fixes

• Erasing on a temporary layer no longer gives negative colors.