Closes #263.

Also fixup some docstrings for better formatting.

This avoids "sparse efficiency" warnings.

This has a lower chance to give an impression that the substitution
happens in-place.

Closes gitlab issue #237

Christoph Groth authored 6 years ago and Joseph Weston committed 6 years ago

and without default values.

Co-authored-by: Joseph Weston <joseph@weston.cloud>

So it's no longer necessary to provide the REFNAME environment variable.
Also the link template string format is now more general to support at
least gitlab github and cgit.

'box-forced' is deprecated as of matplotlib 2.2.

Previously 'plotter.density' was not as well factored as
'plotter.current', which made it hard to compose, e.g. for
passing custom parameters to 'plotter.interpolate_density'.

Also add reference documentation for 'density'.

Thanks to Alexandre Bernard for reporting this.
https://mailman-mail5.webfaction.com/pipermail/kwant-devel/2018-May/000088.html

Previously we used the matplotlib default behavior of setting
the colormap limits (vmin and vmax) to the limits of the plotted
data, if they are not provided by the user. Now we set the
colormap limits to the 2nd and 98th percentile of the input
data, and stretch the limits by 10% on either end in an attempt
to include all the data in the limits. If we cannot do so
we set the limits to the percentiles plus the stretch
and issue a warning.

Also, whenever the data falls outside the colorbar limits
(even when the latter are set by the user) we set the appropriate
ends of the colorbar to be pointy, indicating that the data
extends beyond the colorbar.

Closes #183

This can always be resurrected from Git if it is really needed,
but at the moment its just 3000 lines that aren't used.

Thanks to Tibor Sekera for suggesting this feature.

Previously, in order to not to fix the matplotlib backend, we required
users to import matplotlib.pyplot before calling any Kwant plotting
functions.  This did not have the desired effect, since we did import
`matplotlib.backends` and that also fixes the backend.

Now, both backends and pyplot are imported at the last possible moment
and a warning is emitted if this fixes the backend.

The problem was introduced in commit 7c802539.

Previously the fact that the positive direction of mode
velocity is determined by the translational symmetry vector
of the system was not made clear in the relevant docstrings.

Closes #143.