`yampa`: Deprecate `arr3`, `arr4`, `arr5`

[ivanperez-keera]

The functions arr3, arr4 and arr5 in the FRP.Yampa.Arrow module are not used in the wild. They also don't really belong in Yampa, since they are generic for arrows.

A search online shows that the functions can safely be removed (all the results are from Yampa or Yampa forks):

https://github.com/search?q=arr3+language%3AHaskell+Yampa&type=code

https://github.com/search?q=arr4+language%3AHaskell+Yampa&type=code

https://github.com/search?q=arr5+language%3AHaskell+Yampa&type=code

[ivanperez-keera]

If anyone wants to take this one, please go ahead and send a PR.

There'd only be two commits:

• Commit 1: yampa: Deprecate FRP.Yampa.Arrow.arr3,arr4,arr5. Refs #313.

• Commit 2: yampa: Document changes in CHANGELOG. Refs #313.

The message of the first commit would have to describe why this is happening. Feel free to grab ideas from the issue description.

Please check out the recent history of this repository to see how we normally document commits, and how we link commits to issues in the subject line of the commit messages. Make sure you use Refs <#issuenumber> in the summary line, etc. I like being very regular and explicit with commit messages.