Remove dependence on Boost
Currently, Akonadi depends on Boost in only one component (TypePluginLoader) and for a fairly simple purpose, which is a basic topological sort of a graph to find and filter through plugins for certain mimetypes.
This MR implements a basic breadth-first search of mimetype parents using QMimeType::parentMimeTypes. This means we no longer need to depend on Boost, which will help cut down on compile times by quite a bit
Edited by Claudio Cambra