fielddata: fixed tests!

projector: RotTiltProjector now ends in the correct coord system!
diagnostics: Refined the LCurve class (now saves stuff!)
lorentz: Added preliminary Lorentz imaging functions!

1: Rotate arbitrary axis onto the x-axis (with rotation around z)
2: Tilt around this new x-axis (this produces the tilt series)
3: Rotate back around z, so that the x-axis is where it was before!
Assumption: The arbitrary tilt axis lies in x-y!

costfunction: chisq_m/a now track their results (better way?)
diagnostics: added LCurve class (not finished), comments for SVD
fielddata: properly ordered properties, added plot_field for ScalarField
phasemap: fixed bug for symmetric=False, cmap=None (no proper default!)

Reconstruction

See merge request !12

ForwardModelCharge updated

See merge request !11

KernelCharge

See merge request !9

Kernel charge revision by @migunov

See merge request !1