* Adds support for storage parameter types
This pr adds a new parameter types type, the storage parameter types.
This parameter type supports loading the value from the storage or
returning the given default value.
* Use twox_128
* Update docs
* Update frame/support/src/lib.rs
Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>
Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>