Python-igraph

- Internal changes only.

Chore

- Change maintainer (7).

Chore

- Update download link for yeast (8, 9).

Chore

- Load igraph package when loading this package.

- Compress as xz, in version 2.

Features

- Import igraph.

- Upgrade graphs to igraph 1.5.0.

Chore

- Igraph on CRAN now.

- Turn off Travis and AppVeyor (10).

- Move README.\* to root.

Features

- New `lesmis_*()` functions (krlmlr, 3).

Chore

- Add tests (5).

- Convert documentation to roxygen2 and Markdown (krlmlr, 4).

- Build-ignore.

- README tweaks.