simpeg/simpeg: DC IP upgrades

DC-IP upgrades from PR #650 commits from @sgkang, @thast, @micmitch, @fourndo review from @lheagy, @rowanc1 This release is motivated by enhancing DC/IP packages in SimPEG, and several contributors have sweated on this release for the past several months. There are four main categories that developments have been carried out: Physics Utilities Inversion Directives Highlights of each development is summarized below. Physics Handling Pole-Pole data Mixed boundary condition for Problem2D_CC and Problem3D_CC Easy import for DC and IP problems Now DC and IP can be easily imported:from SimPEG import DC, IP Storing Sensitivity Sensitivity can be stored, and this option can be used in the inversion:problem = DC.Problem3D_CC(mesh, storeJ=True, ...) J = problem.getJ(m) Working DC octree inversion (thanks to @fourndo and @micmitch) This is limited in a specific branch of discretize package: discretize/TreeMesh_CellGrad Regularization and DC problems have been improved to handle octree and working! Mesh generation utility has not been updated in this branch, but will be included in the next release. IP problem has not been tested for octree yet. Utilities for DC and IP problems (thanks to @thast ) Updated StaticUtils IO functions for UBC-GIF codes DCIP2D and DCIP3D add Utils such electrode_separations or geometric_factor Utils are now compatible with all types of survey Survey and I/O IO class for DC problem is initiated, but still requires further developments. Synthetic DC survey can be easily generated using StaticUtils + DC.IO + DC.Survey # Initiate I/O class for DC IO = DC.IO() endl = np.array([[xmin, ymin, zmin], [xmax, ymax, zmax]]) # Generate DC survey object survey = DC.Utils.gen_DCIPsurvey(endl, survey_type=survey_type, dim=2, a=10, b=10, n=10) # Obtain ABMN locations survey.getABMN_locations() # Obtain 2D TensorMesh mesh, actind = IO.set_mesh() # Generate Topography topo, mesh1D = DC.Utils.genTopography(mesh, -10, 0, its=100) # Generate active cells actind = Utils.surface2ind_topo(mesh, np.c_[mesh1D.vectorCCx, topo]) # Drape electrode locations to topography survey.drapeTopo(mesh, actind, option="top") Inversion Directives (thanks to @fourndo!) Add sensitivity weighting directive Update IRLS directive Change to Directive to convert regularization, misfit to ComboObjectiv