Removal of unused functions/classes/methods

The following has been removed:

function/class/method	purpose/source	Action
qse/constraints.py [all]
qse/calc/messages.py [all]
qse.calc.calculator.compare_qbits	ASE	Remove
qse.calc.calculator.equal	ASE	Remove
qse.calc.calculator.Parameters
qse.calc.calculator.Calculator.get_default_parameters	sounds redundant	Remove
qse.calc.calculator.Calculator.reset	Can be used	Repurpose
qse.calc.calculator.Calculator.read	Can be used	Repurpose
qse.calc.calculator.Calculator.get_qbits
qse.calc.calculator.Calculator.read_qbits
qse.calc.calculator.Calculator.set
qse.calc.calculator.Calculator.check_state
qse.calc.calculator.Calculator.get_energy
qse.calc.calculator.Calculator.get_property
qse.calc.calculator.Calculator.calculation_required
qse.calc.calculator.Calculator.export_properties
qse.calc.calculator.FileIOCalculator
qse.qbits.celldisp
qse.qbits.Qbits.set_constraint
qse.qbits.Qbits.constraint
qse.qbits.Qbits.set_celldisp
qse.qbits.Qbits.get_celldisp
qse.qbits.Qbits.get_cell_lengths_and_angles
qse.qbits.Qbits.get_reciprocal_cell
qse.qbits.Qbits.pbc
qse.qbits.Qbits.get_properties
qse.qbits.Qbits.center_in_unit_cell
qse.qbits.Qbits.get_dihedral
qse.qbits.Qbits.get_dihedrals
qse.qbits.Qbits.set_dihedral
qse.qbits.Qbits.rotate_dihedral
qse.qbits.Qbits.get_scaled_positions
qse.qbits.Qbits.wrap