This reverts commit dcf2c79a.

Added support for testing aql files (tests/aql).
Removed alib2integrationtests/ in favour of tests/ directory.

Sorry for a messy commit.
Closes #198.

It really makes no sense to have it inside alib2std component. Moved
into separate tests/ folder.

Run install target of the build process.

We used 'contrib' name improperly [1,2].

[1] https://drewdevault.com/2020/06/06/Add-a-contrib-directory.html
[2] http://www.geschke-online.de/doc/c2646.html

Simplify versioning by CMake. Uses git version in the format
"<major>.<minor>.<patch>.r<commits-since-version-tag>.g<hash>(-dirty)?".

Adapts Doxygen generators to changes in previous commit.

Remove CMakeLists.txt generator scripts from build phase. Replaced with
CMake's GLOB that can re-run every time the build is invoked. We can
also drop the Python dependency now.

Removed header installs which will be redesigned in future commits.

Remove Dot2 algorithm. By default, the interactive window now
does not block CLI. Added overload to override this behaviour.

Closes #199