Merge branch 'development'

Fixed etl::fsm C++03 template definition that was corrupted in 20.10.0

Fixed meson.build

Updated type traits generator

Merge branch 'development'

# Conflicts:
#	include/etl/version.h
#	library.json
#	library.properties
#	meson.build

Updated version numbers

Altered 'unhandled' delegate to tbe the last in the array for the con…

…stexpr vspecialisation.

Added the option to derive etl::message<> from a custom parent class

Updated Arduino examples

Updated version numbers

Define missing macro when cross compiling with clang