Fix highlighted squares for boards with no board texture

When the board does not have a texture, draw a cell normally (with no highlight), and if it needs to be highlighted draw a highlighted rectangle over the cell with **50%** opacity.
Also fix a small coordinates mismatch when drawing

todo:
 - [x] small drawing coordinates fix
 - [x] update drawing of highlighted colors for boards with no texture
 - [x] set opacity to 0.5 for both dark and light highlighted squares