Add basic Python bindings

This merge requests introduces the basic Python bindings to Nektar++ along with some Python documentation.

The functionalities that have been wrapped include:

• LibUtilities
  • BasicUtils
    • SessionReader: CreateInstance, GetSessionName, Finalise
    • ShapeType: wrapped ShapeType enum
    • SharedArray
  • Foundations
    • BasisType, BasisKey and Basis classes
    • PointsType, PointsKey and Points classes
  • LinearAlgebra
    • NekMatrix
• LocalRegions
  • Expansion: GetGeom
  • QuadExp
  • SegExp
  • TriExp
• MultiRegions
  • ExpList: GetNpoints, GetNcoeffs, GetExp, GetExpSize, WriteVTK, GetCoords, FwdTrans, BwdTrans, IProductWRTBase, L2
  • ExpList2D
• SpatialDomains
  • Geometry: GetCoordim, GetGlobalID, FillGeom, GetXmap, GenGeomFactors, ContainsPoint, GetCoeffs
  • Geometry1D
  • Geometry2D
  • MeshGraph: SegGeomMap, QuadGeomMap, TriGeomMap, Read, GetMeshDimension, GetAllSegGeoms, GetAllQuadGeoms, GetAllTryGeoms
  • QuadGeom
  • SegGeom
  • TriGeom
• StdRegions
  • StdExpansion: GetNcoeffs, GetTotPoints, GetBasisType, GetPointsType, GetNverts, GetNedges, GetNfaces, DetShapeType, GetShapeDimension, Integral, GetBasis, FwdTrans, BwdTrans, IProductWRTBase, PhysEvaluate, L2, GetCoords
  • StdQuadExp
  • StdSegExp
  • StdTriExp

This branch also:

• fixes the error in which for n-dimensional Nektar matrices the transpose was obtained,
• introduces a #define NEKPY_WRAP_ENUM_STRING_DOCS declaration allowing to wrap enum types with a Python docstring included,
• includes Python documentation for Points, PointsKey and PointsType classes (accessible using help() function).
• closes #107 (closed) and #96 (closed)