Fixes #2

- updated version to v0.3.0 as API changed
- ConstSizeTiles.__getitem__ -> (x_offset, y_offset, x_extent, y_extent), (x_out_size, y_out_size)

Fix long description of setup.py to match pypi conditions

Update docs conf.py, Readme, tests and version

Add sphynx docs

Update example, change stride behaviour if scale is not 1.0