## Issue:
Hey, not sure if this is disallowed for any reason specifically, but it would be very beneficial to define additional types to decode tendermint key implementations from bytes, since it uses a static codec. If this is okay, let me know and I will add documentation.
Context: For Ethermint to switch to using Cosmos' keybase, decoding the keys requires this codec to be updated
Just to document, I did experiment with creating a mapping from string to objects to be able to keep track of the key types added to be able to be used in the RegisterAmino(..) call, but because of how go is compiled, cosmos would just use the base types. This may be a useful feature for someone just building on top of Tendermint and not going through Cosmos, but to not add confusion or unnecessary complexity, I left it out.
## Commits:
* Exposes amino codec to be able to decode pk bytes in application
* Change how codec is modified
* Remove unneeded comment
* Fix comment
* Fix comment
* Add registered type to nametable
* Add pending changelog entry
* Reorder change
* Added check if type is registered and added test
* Make test type private
* Remove unnecessary duplicate exists check