- removed ugly fix in transf mesh of tri surf
- use MFaceVertex params in boundary mesh if available
- cleanup intro chapter in docs

more occ work

start opencascade integration

make negative physical entities behave like they're supposed to

- setParameter in MVertex
- revert() for quad
- minor cleanups in I/O code
- start work on overlap mesh in fourierModel

- better computation of bounds for discrete entities
- added small widget for light position selection
- infrastructure for Fourier models