merged branch fabpot/env-simplifications (PR #904)

This PR was merged into the master branch.

Commits
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0a7b37b changed the way extension filters/tests/functions/node visitors/globals/token parsers are registered (they were loaded as late as possible, they are now loaded as early as possible)

Discussion
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simplified some code

This PR changes the way extension filters/tests/functions/node visitors/globals/token parsers are registered (they were loaded as late as possible, they are now loaded as early as possible)

It mainly consists of a code cleanup by removing the horrible staging hack we have now.