Adding a layout for Ensoniq ESQ-1.

- It can play notes by clicking on the keyboard.
- Volume and Data Entry sliders are hooked up via Lua scripting.
- Volume slider still non-functional. Data Entry slider works fine.
- SVG snippets were kept to the absolute minimum (drawings of envelope and oscillators diagrams)
- The full unit was drawn, but only the relevant part is visible on the
  default layout. We may later add other views such as "Full keyboard".

Author: felipesanches