pino 2.16.0

This release gets the 2.x branch up to date with the latest bug-fixes and new features from master and as such include all non-breaking commits that have been released from v3.0.0 up until v3.1.0, including:

Improve the error serializer #146 #157 by @satazor @colmose @mcollina
Fix prettifier error when receiving null value input #154 #155 @jsumners
Split README into multiple files for better organization #152 #153 @jsumners
Reduce the size of the package #137 #136 @osher
readme tweak fix @davidmarkclements
Condense README #143 by @davidmarkclements
Fix for #139, #141 by @mcollina
added pino-debug to readme - #133 - @davidmarkclements
improved deep object interpolation performance and fixed double escaping bug #129 by @davidmarkclements
Open Open Source #127 #118 by @mcollina
Refactor the internal constructors #125 by @mcollina