Pylandstats

- corrected shapely version in setup.py (bumpversion messed it)
- updated bumpversion for release candidates
- catch TypeError for existing metrics but at the wrong level
- always import modules, not methods/classes
- consistent API: all data frames obtained with `compute` methods

- corrected rst typo in `total_area` docs
- fixed missing perimeter distribution statistic metric and dried class constants definitions
- fixed patch edge array computation when computing ENN (otherwise the speed-up of 1.1.0 is not effective)

- speed-up (~x2) in `Landscape.compute_patch_euclidean_nearest_neighbor`: compute pixel-to-pixel distances for patch edges only

- fix landscape array dtype in `SpatioTemporalBufferAnalysis`
- included `LICENSE` in `MANIFEST.in`

- deleted Python 2 classifiers in `setup.py`
- fix ValueError message for `landscape_crs` and `landscape_transform` in `BufferAnalysis`
- fix landscape array dtype in `GradientAnalysis` and `BufferAnalysis`

- dropped Python 2 support
- added `SpatioTemporalBufferAnalysis.plot_landscapes` method
- added `buffer_dist_legend` argument and docs in `SpatioTemporalBufferAnalysis. plot_metric`
- fix proper metric data frame properties in `SpatioTemporalBufferAnalysis`
- pass `transform` argument when initializating `MultiLandscape` instances (i.e., `SpatioTemporalAnalysis`, `BufferAnalysis`, `GradientAnalysis` and `SpatioTemporalBufferAnalysis`)
- `plot_landscape` and `plot_landscapes` with rasterio.plot.show
- changed `feature_{name,values}` for `attribute_{name,values}` in `MultiLandscape` (abstract) class
- dropped `plot_metrics` method