Envisage 6.0.1

This bugfix release fixes the issue where Extension Point resolution was
happening too eagerly, which caused issues during application startup time in
certain cases. We recommend all users of Envisage to upgrade to this bugfix
version.

Fixes

• Revert PR #354, which caused the issue #417. (#422)

Tests

• Ensure that the testsuite passes with minimal dependencies. (#423)
• Add a regression test for issue #417. (#421)