…r, ComplexOperator, and the parallel (unassembled) ParOperator and ComplexParOperator

This is a first step towards removing a lot of the dependency on PETSc for complex-valued linear algebra and streamlining the interface to support partial assembly. Includes the necessary changes for SpaceOperator, CurlCurlOperator, and LaplaceOperator in the matrix and vector construction. Also updates operator construction from driver classes. Next up, linear solvers.

…SP, with reworking to add ParallelAssemble in various solvers which require HypreParMatrix operators

TODO: Work into all driver classes.

…static, magnetostatic, transient

…genmode simulation types

Eigenvalue solver updates applied to SLEPc and ARPACK, not FEAST yet. Need to incorporate into wave ports too.

…or parallel assembly and system matrix construction, as well as AMS upgrades

…and no adaptive frequency sweeps and eigenmode solves

Bug fixes include: ComplexVector AXPBY and AXPBYPCX with uninitialized vector, ParOperator real-valued mass matrix orthogonalization for eigenvalue solves, unique_ptr<T[]> array construction, remove unused FEAST code (for now), remove unused PETSc code, SLEPc function pointer fixes, and others.

…t least until SubMesh is supported for ND spaces

…pecialization

…and complex-valued operators, as part of a new Solver<OperType> class

… algebra and operator wrappers for complex-valued linear systems

…or, CurlCurlOperator after refactor

…solvers and operator types

…ansient)

…al guess

…using Eigen for PROM dense matrix operations

…functionality and wave ports

Reverts prior commit as this idea did not work, one boundary attribute may touch many domain attributes.

… S-parameter calculations

…unicator is different than the solvers (for example, many processors with empty local matrices)

… smoothers

…nSolver -> Arpack/SlepcEigenvalueSolver, using instead of typedef, fix some typos in comments

…with a mutable RAP member to avoid some const_cast, clarify some comments, use initializer lists where possible for constructors