Added a new directory for GDB scripts.  Currently there's only one, but it shall grow.
Verts are now stored in vectors of shared_ptrs which belong to objects; Polygons now reference them by index.  Currently it's a little messy and pointless,
but the idea is that eventually I can reduce the dependency on floating point tolerance by having Polygons only use a vert's actual value when absolutely necessary
(such as the split method).  Whenever possible, polygons will use the index of a Vert instead.  This will also allow me to change the vector of shared_ptrs to Verts
to a vector of Verts, which will improve CPU cache performance.

Also added a new test case, tests/mug_bad.csg.  This case has some missing polygons.  At first I thought it was a regression, but it was not introduced by this commit.
I must continue to investigate.
Merge branch 'master' of https://github.com/jayelliott/geomorph
Backout stupid mistake I did during the last commit.