Before this change when you set a prompt, you have to do the following:
```rb
Pry.config.prompt = Pry::Prompt[:simple][:value]
```
The `[:value]` part was leaking implementation details and it proved to be an
unnecessary step.
With this change we can do the following:
```rb
Pry.config.prompt = Pry::Prompt[:simple]
```
`[:value]` is omitted.
I have also refactored some tests and removed irrelevant ones.
The Array API for prompt is deprecated:
`Pry.config.prompt = [proc {}, proc {}]` emits a warning now.
let's try to avoid exotic heredoc syntax that GitHub and multiple
editors cannot support, the only confirmed editor that supports
highlighting this syntax so far is 'emacs'.
it is not friendly to non-emacs users to have to deal with broken
syntax highlighting, especially when there is a less exotic and
easier syntax available.
the list-prompts command shows a list of available prompts as well
as the active prompt in the list. prompts are drawn with a name as
well as a short description.
change-prompt can be used to change the prompt by the name found in
the list-prompts command.
