Bindable Inverseoperator

This branch introduces the possibility to construct inverse operators without a operator (and preconditioner) and bind a operator to it later. Additionally the branch adds a constructor to NewtonInverseOperator which moves its LinearInverseOperator.

TLDR:

• adds bind(op) (resp.bind(op,prec)) and unbind() methods to inverse operators.
• adds constructor without operator to inverse operators.
• adds setMaxIterations(unsigned int/int) to inverse operators, additionally add setMaxLinearIterations(int) to NewtonInverseOperator.
• adds test which covers inverse operators (see below for some caveats).
• makes most solvers movable.

Done

• NewtonInverseOperator [newtoninverseoperator.hh]

• CGInverseOperator [cginverseoperator.hh]

• ParDGGeneralizedMinResInverseOperator, ParDGBiCGStabInverseOperator [pardginverseoperator.hh]

• ISTLLoopOp, ISTLCGOp, ISTLBICGSTABOp, ISTLMINResOp, ISTLGMResOp [istlsolver.hh]

• ISTLInverseOperator [istlinverseoperator.hh]

• EigenCGInverseOperator, EigenBiCGStabInverseOperator [eigen.hh]

• PETSCInvereOperator [petscsolver.hh]

  untested

• OEMCGOp, OEMBICGSTABOp, OEMBICGSQOp, OEMGMRESOp [oemsolver.hh]

  OEMGMRESOp is broken, see #51 (closed).

• GMRESOp, FGMRESOp, BICGSTABOp [oemsolver.hh]

  FGMRESOp fails an assert when used without preconditioning.

depends on !120 (merged), !121 (merged)