Kwant no longer needs linking against Lapack directly, as
we use the Lapack provided by Scipy.

Previously, the numpy 'include_dirs' would be shadowed by
any 'include_dirs' provided in 'build.conf'. We want to avoid
burdening people with remembering to specify the numpy 'include_dirs'
every time, and if custom numpy headers is the desired behaviour, these
can still be specified in 'build.conf', and will take precedence.

The warning used to be emitted from build_discretized().  Whenever
discretize(), another API function that internally calls
build_discreitzed() would be called with the deprecated argument, a
warning would appear for a line in the code of discretize().

This has been fixed by factoring out the check, and calling it from both
functions.

Use the matplotlib color cycle for site families when
calling 'kwant.plot'.

Closes #141, see !162.

Pull in fixes for Cython 0.26.

We can now use Scipy's Cython interface to Lapack, which removes the
need for us to explicitly link against blas or lapack ourselves. Also
cut down boilerplate by re-arrange the existing Lapack wrappers to use
Cython fused types.

Closes #28

We use Cython's import mechanism to use the the same lapack used
by Scipy, so we no longer need to explicitly link against lapack
or blas.

This reverts commit 1e6c0860, reversing
changes made to 2c5da944.

The changes to Kwant's Lapack wrappers depend on features from
Scipy 0.16, so it cannot be merged into stable branch, which
depends on Scipy 0.14.

fix pickling on Cython 0.26

See merge request !175

Closes #170

Our oldest supported distribution is Ubuntu 16.04, which ships
with Python 3.5.

Closes #169

enable PDF documentation builds

See merge request !171

Produce vector graphics, rather than rasterizing,
as rsvg-convert does.

Add the 'unicode-math' package and set the
latex engine to 'xelatex'.

Closes #126.

improve 'attach_lead' docstring

See merge request !170

sympy is installed in the Kwant testing image now.

We can now use Scipy's Cython interface to Lapack, which removes the need for us to explicitly link against blas or lapack ourselves. Also cut down boilerplate by re-arrange the existing Lapack wrappers to use Cython fused types.

Closes #28

See merge request !149