Boundaries of the (b-type) deflector

[timber-they]

• The deflector has a special shape
• This should be implemented as a boundary (contrary to just using the NaN values as boundary)
• For this one needs the analytical description of the boundary of the deflector and then detect whether the molecule is inside this boundary
• The detector probably is a (3D extended) rectangle minus two ellipses -> the particle hit the boundary if it is outside the rectangle or the ellipses
• At some point other deflectors (e.g. a-type) should be supported as well