The revised patch from Leon for new particle effects.

The revised patch from Leon for new particle effects.

New is that objects can have a force field, and Meshes can even deflect
(collide) particles. This is in a new sub-menu in Object buttons F7

The full instructions where on the web, Leon mailed it me and I will put
it in CMS tomorrow. For those who like to play with it now, here are demo
files:

http://download.blender.org/demo/test/

Quite some changes where in the integration though... so previous created
particle deflectors will not work. Changes to mention now are:
- gravity is renamed to 'force field'
- force field and deflector options are in Object now, not in Mesh
- the options also have its own struct, doesnt add to Object by default
- force fields are possible for all object types, but only work on center.
  So empty objects are typical for it.

Work to do:
- add draw method in 3d win to denote forcefield objects
- check on the UI (panel with different size?)
- add 'recalc' button in deflector panel