Remove dependency on ocamlgraph. Dead code only.
As_project: reorder things logically.
As_project: (internal) rename parents to path_to_root.

As it includes the component you apply the fun to.
As_project: rename Component.source to Component.source_dir

This is what it is.
As_project: rename Component.filter to Component.filter_map.

That name is more accurate.
As_project, add Component.keep.

This is really filter, but filter by itself is ambiguous it's unclear
whether you filter out or filter through.
Let Pkg components have phases & write phase variables in Makefile.

We don't use them yet.
Move As_project.Component to As_component.

Other submodules of As_project go in As_component. Constantly
refering to As_project.Component.bla was becoming annoying.
Fix documentation generation.
Reverts commit 43175fb. Pkg components no longer write vars in Makefile.
Merge pull request #94 from dbuenzli/split-component-from-project

Split component from project