fix surfperiodic

more occ work

more occ work

:i

occ work

more occ work

occ work

start opencascade integration

hide entities by clicking on them

added getNumPrimaryVertices (num vertices for a first-order element)

- routines added for finding all or some of an elements neighbours
- many miscellaneous changes and some reorganization

finish Mesh>Edit>Delete

polish gui for navy demonstrator

make Mesh>Delete and Inspect more robust (allowing to change mesh
by other callbacks while in selection mode)

new Mesh>Inspect to get individual ele info

more mesh edit work

small optim

fix labels

much faster element deletion algorithm

mesh edit

better GUI for clipping box

more work on mesh editing

start work on mesh>edit feature (delete elements, etc.)

Only 2D elements have been tested