Model R: investigate the limitations of icons rendering

[grdddj]

Currently, there are a couple of limitations regarding icons/images:

• TOIF format does not work with odd-width icons, so we need to leave one column blank when the icon is odd-wide
• we cannot start drawing icons at an odd x coordinate, which means the icon needs to be also modified for this
• it seemed that when the height was odd, it refused to draw the last line - so all icons need to be even even-wide

It would be nice to get an idea of how difficult it would be to fix these, as it would make the precise-pixel-work easier.