whatnext 3.0

Breaking change: @after filenames are now resolved relative to the
file containing the directive, supporting

@after ../project-b/setup.md
@after subtask/notes.md
@after ~/tasks/dependency.md

Previously whatnext assumed a flat hierarchy of unique filenames.

Added:

• @phase directive in section headers creates a dependency chain within
  the file; the first phase is always visible, and subsequent phases
  will only show when all previous phases are complete.

Fixes:

• @after referencing a file excluded by --ignore no longer warns about
  the file not existing, instead treating the dependency as complete.

---

pypi release