Fatiando a Terra v0.3: Modeling and inversion in geophysics

Fatiando a Terra (Portuguese for Slicing the Earth) is an open-source Python toolkit for modeling and inversion in geophysics. It provides an easy and flexible way to perform and implement geophysical data analysis.

Official website and documentation: http://www.fatiando.org

Changes to version 0.3:
* New module fatiando.gravmag.normal_gravity
* **BUG FIX**: fatiando.gravmag.prism gravitational field functions now give correct results in all sides of the prism as well as inside.
* PEP8 compliance (started by @SamuelMarks)
* Cython implementations of fatiando.gravmag.sphere and fatiando.gravmag.polyprism.
* Multithreaded parallelism with OpenMP in fatiando.gravmag.sphere, fatiando.gravmag.polyprism and fatiando.gravmag.prism. Speedups are range from practically none to over 3x. Works automatically. Windows users will have to install an extra dependency! See the [install instructions](http://fatiando.readthedocs.org
* New class LCurve in fatiando.inversion.regularization for estimating the regularization parameter using an L-curve criterion.
* New module fatiando.gravmag.magdir for estimating the total magnetization vector of multiple sources.