Major rewrite of several parts of the code in order to abstract it and make it easier to use and expand.

It implements a unified interface for theoretical fields and data maps.

Stats:

• Minkowski Functionals support theoretical fields and data maps
• Extrema statistics: maxima and minima (experimental)

Theory

• Gaussian and $\chi^2$ fields are easier to define in any dimension
• Easy interface to define Spherical Gaussian and $\chi^2$ fields from their angular power spectrum

Data

• Healpix maps
• Easy interface for $P^2$ maps