Fixes#1843 (Rework the Pry config)
There are a few breaking changes. They are mostly minor, so I decided not to
indroduce deprecations because it will considerable slow things down.
Key changes:
* `Pry.lazy` was replaced with `Pry::Configuration::LazyValue`
The config accepts three values now `LazyValue`, `MemoizedValue` and simply
`Value`. The main difference is that:
- `Value` is any value, including procs (so that an option returns a raw
proc)
- `LazyValue` is a proc that is call on every invocation of an option
- `MemoizedValue` is a value that is called only once (and then the option
always returns the return value of the )
* `Pry.config.history` was a meta-option that held suboptions. However, the new
config doesn't permit that (unless you know what you do)
Instead, we introduce a few options. For example:
- `Pry.config.history.histignore` becomes `Pry.config.history_ignorelist`
- `Pry.config.history.file` becomes `Pry.config.history_file`
- and so on
This was done so we can simplify configuration merging. Inlining option makes
configuration implementation simpler, without losing much. The rule is that
you want to keep your options under your prefix (if you are a
plugin). Therefore, say, `Pry.config.pry_rescue.*` should be
`Pry.config.pry_rescue_*` if you need merging.
The rest should behave in a similar fashion (and I rely heavily on our test
suite to claim so).
