Fix typo, comment out unused variables.
Small fix regarding std::complex display in QT.
Fix typo.
Add qtHide: a hack to hide incompatibility DEM vs. QM

FIXME: Implementing Quantum Mechanics makes some DEM assumptions
invalid. I think that we should rethink what base classes like State and
Body really must contain. So that in QM we would not need to use this
hack to hide some variables.

However it is great to note that only this little 'cosmetic' hack is
needed to make Quantum Mechanics possible in yade

See also:
class WaveFunctionState,
class QuantumMechanicalBody,
gui/qt4/SerializableEditor.py

So in fact if we decided to fix the inheritance tree we should remove
attributes listed in qtHide from the base class and make derived classes
like:

class DiscreteElementBody: public Body;
class DiscreteElementState: public State;

Just like I just made classes:

class QuantumMechanicalBody: public Body;
class QuantumMechanicalState: public State;

Probably similar things happen with shape and material, but it is less
pronounced, since base classes for shape and material are more "empty".
There is only one attribute meaningless for QM: material.density