Release 0.4.0

Changes from 0.3.3 to 0.4.0

• API renaming. The function names simulate a namespace and some
  variable names have been changed to those used by the general community
  (part -> chunk).

• Add a new level of multi-dimensionality. As a result, unlike other
  libraries, Caterva supports two levels of multi-dimensional chunking (chunks
  and blocks).

• Improve library compilation to allow users to avoid building tests and
  examples.

• Simplify the test's suite for a proper integration in Windows.

• Update documentation to improve the library description and to add the
  Release notes and the Roadmap in a new section.