Rename and clean up files.

[devinamatthews]

• Rename all header files with "tapp_" prefix. This will help prevent problems when users do something like #include "tapp_XXX.h" with -I/path/to/tapp/tapp.
• Remove some old discussion and proposal files.

[janbrandejs]

I think this would be an efficient scheme which we could potentialy require anytime when the interface itself is changed in multiple places:

1. there is a pull request on tapp interface itself
2. reviewer thinks it's a good idea
3. put the suggested changes on a branch in reference implentation
4. test passed (pipeline test++?) -> you can merge in master there without a review
5. the pull request to tapp itself can be approved

[devinamatthews]

Yes definitely any changes should go through CI and the ref. implementation is a good place for that. I need to make sure we are starting from 1:1 on the interface defined here and implemented in the reference.

[devinamatthews]

Just a couple more PRs here then I'll work on that flow :).

[devinamatthews]

Except, I'm not sure about steps 1 and 2 since that will be a lot more work for maintainers. Perhaps it would be good to keep development (including interface) on the reference implementation master branch and then group updates atomically into new versions of the official interface.

[janbrandejs]

Excellent idea!