Updated getting-started-dev.rst doc and fixed some broken links

Merged Bitbucket Importer requested to merge bitbucket/merged-pr-140 into branch/default

Created originally on Bitbucket by tilarids

Was already merged in Bitbucket before import, marked as merged by the import user

  • Docs for several RPython env vars were added
  • translatorshell.py sets sys.path correctly now
  • Broken extradoc link was fixed

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