Add hinged lids to WallHopper

[AlexCPU]

By suggesting a new box generator or other feature you agree to test cut it until it works. You understand that this may take a few attempts. As soon as it does work you will provide a sample image that can be used in the user interface or the documentation.

Describe the solution you'd like
WallHopper generator has optional hinged lids for the top and bottom. As proposed in #734

** Pictures of something similar **
Basically this, but fixing the overlapping cut lines on the hinge.

[florianfesti]

There are a few other tickets open against this edge already: #576 and #372

It needs to become a little more versatile to adjust to more situations - preferable including this one.

[florianfesti]

OK, setting the style to "flush" should at least solve hopper situation. Although drawing the sides by hand allows it being even nicer.

"Flush_inset" might work with the top - although not quite as sturgy as one might want. The issue here is that the wall edges don't leave any meat on top for the hinge to connect to. A small piece E or F edge added using a CompoundEdge might solve that.

Note that I just changed the style business in d4b238c