Simpeg

Docs
- A beautiful Examples Gallery. Thanks rowanc1!!
- cleanup travis deploy of docs
- add an "edit on github" link for each page of docs
- patch for properties docs when inheriting and extending a property (see 3ptscience/properties153)

Other changes
- travis testing on python 3.6
- deploy to pypi from python 3.6
- update to be consistent with latest properties release (https://github.com/3ptscience/properties/releases/tag/v0.3.3). Thanks fwkoch!

Major changes: discretize
- removed the meshing, and some of the testing in favour of `discretize` (which was pulled out and improved by jcapriot)
- There are major updates to Richards equation and a number of new examples. This includes the ability to invert for any parameter inside the empirical functions.
- `np` and `sp` are no longer exported by `from SimPEG import *` 533

Minor changes
- Removed `utils.isScalar` in favour of the numpy version.
- `Identity` and `Zero` are pointers into the `discretize` package
- Validation on `HasModel` classes is now recursive.
- Updated testing code to latest version of `pymatsolver`, backwards compatible.

TDEM: Four formulations
- `Problem3D_e` : can solve for `e`, `dbdt`
- `Problem3D_b` : can solve for `e`, `b`, `dbdt`
- `Problem3D_h` : can solve for `h`, `j`, `dhdt`
- `Problem3D_j` : can solve for `j`, `dhdt`

Namespace

Following conventions in FDEM
- Receivers are classes: `TDEM.Rx.Point_dbdt`. This will break backwards compatibility

Testing
- Cross check `Problem3D_e` and `Problem3D_b` against each other, as well as `Problem3D_h` and `Problem3D_j` against each other
- Derivative and adjoint tests on all using a step-off waveform, mag dipole source
- Derivative and adjoint tests in off-time for a vtem waveform

Other Items
- started implementation of `properties` in Sources
- use `_formulation = 'EB', 'HJ'` instead of `eqLocs`
- abstract common pieces of `FDEM`, `TDEM` sources to a `BaseEMSrc`

changes from 539

Properties
- SimPEG now depends on `properties[math]` (https://github.com/3ptscience/properties)


pip install properties[math]


Mappings and Models
- depreciate `mapping` in the problem definition. Now the physical property to which the mapping is related must be explicitly stated. eg.
`SimPEG.EM.FDEM.Problem3D_e(mesh, mapping=sigmaMap)`
becomes
`SimPEG.EM.FDEM.Problem3D_e(mesh, sigmaMap=sigmaMap)`
This change is not backwards compatible
- depreciate `problem.curModel` in favour of `problem.model`
- implement `properties` for the physical properties in all SimPEG problems

Added Maps
- Parametrized block in layer
- Parametrized layer

EM
- break `SrcFDEM` out of survey and put into a separate file
- implement primary-secondary source for FDEM problem
- testing of sources for FDEM

Static
- tests dipole-dipole, dipole-pole, pole-dipole, and pole-pole
- corresponding pole source and receiver classes are implemented
- option for boundary conditions for Problem3D_CC (dirichlet or neumann)
- consistent handling of null-space for both Problem3D_CC and Problem3D_N
- 2.5D DC code is implemented (`Problem2D_CC` and `Problem2D_N`), and tested
- Useful utiilities
- `plot_pseudoSection`: plotting pseudo-section for 2D data
- `gen_DCIPsurvey`: generating simple surveys
- read/writeUBC_DC3Dobs
- readUBC_DC2D model
- convertObs_DC3D_to_2D: Collapse 3D survey to along line 2D survey
- Analytic functions are added: `DCAnalytic_Pole_Dipole`, `DCAnalytic_Dipole_Pole`, `DCAnalytic_Pole_Pole`, `DCAnalytic_Dipole_Dipole`, `DCAnalyticSphere`

Mesh View
- added the ability to do `mirror=True` on the cyl mesh and have it plot a mirror image so corss sections can be easily viewed
- added the ability to down-sample the area being viewed using `range_x`, `range_y` to define the bounds of the region you want to view. `sample_grid = [dx, dy]` can be used to re-sample the data (handy for the casing-type meshes)

Examples
- so much whitespace cleanup :)
- add Craig's example: PF_Gravity_Laguna_del_Maule_Inversion
- add examples from SimPEG.EM paper

Docs
- deploy: http://dev-docs.simpeg.xyz

- add projection map
- use creative commons footer in docs

Refactoring of Natural Source Electromagnetic Implementation. Includes Magnetotellurics, Tipper and ZTEM (minimally tested). From PR's 462, 423
- `NSEM` inherits from `SimPEG.EM`
- `SimPEG.MT` --> `SimPEG.EM.NSEM` : inherit all natural source EM functionality from `EM.NSEM`
- namespace has been updated to be consistent with `SimPEG.EM.FDEM`, in particular all problems follow the convention `ProblemXD_assumption` where `X` is the dimensionality of the problem
- `NSEM` receivers are now classes
- `RX.Point_impedance3D`, `RX.Point_impedance1D`, `RX.Point_tipper3D`
- `NSEM` have been renamed `Planewave_...`
- Documentation for NSEM

known issues and further development are covered in 452