Get rid of custom Enum (fixes #645)

[leplatrem]

Isolated commit about Enum from #647

@tarekziade r?

[leplatrem]

The .value everywhere bother me a bit, but I think it's sane to use a standard enum.

@almet @Natim any strong thought against it before we merge?

[Natim]

The .value everywhere bother me a bit, but I think it's sane to use a standard enum.

Same feeling, same conclusions.

[almet]

yeah, it seems we're all there :-) Merging.