pinout_preview should be more generic

[Chad Parker]

This is wishlist item for a rainy day.

The pinout preview window is a small window in the gtk hids that will show an element and it's pinout.

It would be nice if this were a more generic widget that you could use to preview any pcb data. Such a widget would be useful for example:
* in the preferences window for illustrating say, fonts, grids, sizes
* in a DRC window to show the user exactly which two items are violating and how
* in a "clarification" window that might pop up if you clicked in a place where there were multiple possible things you could have intended to click on.