Renaming of variables in PhaseMapperRDFC.jac_T_dot to make more sense...

New API module unclutters the namespace (import pyramid.api as pr).

phasemapper: Now without fft.shift (not necessary thanks to fft.fftfreq)
magcreator: Now vortices with orientation along negative axes possible.
fielddata: HDF5 load updated to new HyperSpy BaseSignal (all signal axes now...)

Refactoring: Replaced MagData with VectorData and added ScalarData class (and common superclass FieldData).
magnitude is now called field (which is more appropriate)
projector now uses FieldData to process both vector and scalar data (foundation was in place before)

fieldconverter: methods to convert M to A to B
magdata: a bit more parameters for quiver_plot3d(), added contour_plot3d()
phasemapper: pm() extended for different projections (not just simple)
kernel: u and v switched (now named after the unit magnetization direction, which makes much more sense)