Summary:
This is actually not needed. All functionality we use is provided by the Qt meta object system.
There's one feature we loose: Listing the extensions of a plugin
(IPlugin::extensions()); which is never used however. I don't see it being overly useful either.

Simplifies plugin development a bit.

Subscribers: kdevelop-devel

Differential Revision: https://phabricator.kde.org/D3774