Compdb

In this release:

* Rework the headerdb generation from the ground up.
The new implementation just build a graph of the included-by relationship between files.
* Support JSON Compilation Database `arguments` and `output`.
* Support simple quotes in JSON Compilation Database.
* Support logical paths in JSON Compilation Database.

In this release:

- fix packaging: go back to universal wheel
- Travis-CI fixes

New versioning scheme, test new packaging method.

Main change in this release is the removal of the `headerdb` subcommand. ;)

It has been superseded by a more opinionated `update` command and the concept of "complementer".
`dump` and `find` have been replaced by a single `list` command.

Main feature in this release is the `headerdb` subcommand.