Utility for calculating the ccw sweep. The sweep is useful to determine where labels can be placed.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Rename sweep() to extent().

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Reorder hydrogen positions and include the direction each position is pointing.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>