DOC: add human-readable CHANGELOG

Author: pavoljuhas

CHANGELOG.md

@@ -0,0 +1,32 @@
+# Release notes
+
+Notable differences from version 1.1.
+
+## Unreleased – Version FIXME
+
+### Added
+
+- Support for Python 3.7, 3.6, 3.5 in addition to 2.7.
+- Makefile targets `module` and `test`.
+- Support installation from a tagged git-archive tarball.
+
+### Changed
+
+- Build Anaconda package with Anaconda C++ compiler.
+- Allow language standard c++11.
+- Update to diffpy.structure 3.0.
+
+### Deprecated
+
+- Variable `__gitsha__` in the `version` module which was renamed
+  to `__git_commit__`.
+
+### Removed
+
+- Support for Python 2.6.
+
+### Fixed
+
+- Windows build with MSVC 9 and MSVC 14.
+- Invalid escape sequences in string values.
+- Open files within the `with` context so they get closed when done.