Add panelreel class

[dankamongmen]

We need extract the panel wheel code from https://github.com/dankamongmen/omphalos and https://github.com/dankamongmen/growlight, unify it, and add it to outcurses.

To handle both growlight and omphalos, we'll need at least:

• libpanelw-based boxes, with the option to leave a side off
• controllable expansion of said boxes
• moving among boxes
• moving among boxed elements
• box content-filling
• wheel UI

[dankamongmen]

It's been added as of 0.0.4. We now need more refined work (callbacks, tablet draws, etc.).