[eclass] Call 'default' instead of replicating the default implementation as per review from pesa.
[eclass] Use '[[' instead of '[' as per review from pesa.
[eclass] Make doxygen generation work again.
[eclass] Avoid dohtml as per review from pesa.

It will be deprecated beginning with EAPI 6 and banned beginning with EAPI 7.
Update .travis.yml

Use python 3.4