User Experience: Fix `optimize_kl` minisanity plotting for runs with many parameters

See merge request !821

change from last to latest

See merge request !839

don't open new fig in every iteration

See merge request !838

remove note mpi tasks in sample_list

See merge request !836

add missing "not" in changelog

See merge request !837

Sampling: Do not raise on not converged samples

See merge request !835

Better Lanczos interface

See merge request !832

re: cg: Relax energy error criterium within Newton

See merge request !833

HarmonicSKI: Make pad symmetric

See merge request !834

Operator: activate partial_insert by default

See merge request !790

FIX: add missing sqrt, save real std

See merge request !830

Implement refinement of HEALPix

See merge request !809

Do not enforce a specific dimension where unnecessary (e.g. in
`HEALPixChart`). However, do so where the computation either would fail
or would produce bogus results if invoked with fewer or more dimensions.

AbstractModel: Dynamically initialize attr

See merge request !831

SciPy does not compute the energy, so at least we should not do worse
than SciPy...

Approximates tr(log(M)) using tr(log(T)) where T is the projection of M
into the krylov subspace K(M, v) where v is a sample from the metric M
(i.E. v = v_lh + v_pr where v_lh/v_pr are samples from the
likelihood/prior metric, respectively. In addition, the projected sample
is constructed by taking v_pr projecting out the subspace K(M,v) using
its eigen-basis. This ensures that both, the prior dominated part of v
and the part already covered by tr(log(T)) is projected out.

Original author: Philipp Frank

Drop unused code blocks and refactor the geomap energy computation.

Furthermore, add a remark on the necessity of sampling antithetically.