Move dispatch and transform modules to fasttransform

[RensDimmendaal]

This PR can't be merged before the nbdev PR has been merged.

This PR removes the fastcore.dispatch and fastcore.transform modules as they have bent extracted to a separate repository: fasttransform.

Open questions for Jeremy:

• verify: is the update to version 1.8.0 sufficient or should it go to 2.0.0? (1.8.0 is minimum to not break latest fastai release as it pinned: fastcore>=1.5.29,<1.8)
• verify: get_source_link in xtras.py has been updated to be compatible w plum, but we don't add plum as a dependency to fastcore as we want to keep fastcore dependency free. Shall we add a test and add plum as a dev dependency though?
• ./fastcore/_nbdev.py still has references to the old nbs, not sure why it isnt updated. Is it still used? Last change in that file is 3y ago.
• update CHANGELOG.MD

[jph00]

• verify: is the update to version 1.8.0 sufficient or should it go to 2.0.0? (1.8.0 is minimum to not break latest fastai release as it pinned: fastcore>=1.5.29,<1.8)

I'm happy to use 1.8.0 if you think that'll work ok.

• verify: get_source_link in xtras.py has been updated to be compatible w plum, but we don't add plum as a dependency to fastcore as we want to keep fastcore dependency free. Shall we add a test and add plum as a dev dependency though?

Adding a test and dev dep could be a future PR if we wanted.

• ./fastcore/_nbdev.py still has references to the old nbs, not sure why it isnt updated. Is it still used? Last change in that file is 3y ago.

I guess not - could be a future PR.

• update CHANGELOG.MD

That's handled automatically.

@RensDimmendaal let me know if you think this is ready to merge.

[jph00]

All tests are now passing except the fastai integration tests (which will of course require the fastai PR, so we can ignore them here).