Fix changelog v0.9.2 timestamp #typo
Revise CHANGELOG formatting

"version 0.9.2" and "Version 0.9.2" both look weird to me

2013-04-2 is inconsistent, changing to fixed-width format 2013-04-02

Don't refer to issue only by number, use short text description.

Use descriptive names for categories of changes.

List categories of changes in order from most outward-facing to least:
feature changes, bugfixes, internal refactors, build system changes

Make category-of-changes headings bold rather than list items, so they
stand out more while taking up less space.
v0.9.3