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

Fixed meson.build

Added a Bipartite buffer

Added a Bipartite buffer, by Benedek Kupper.
etl::bip_buffer_spsc_atomic
notify_observers() takes universal reference for C++11 and above.
Updated type traits generator.

Changed std::forward to etl::forward in etl::variant (variadic)

Merge branch 'development'

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

Variadic version of etl::variant + refactoring of type traits

Added a vaiadic version of etl::variant. Usable for C++11 and up.
Added etl::overload pattern class. Groups lambdas into a functor class.
Refactored type_traits.h. Uses STL, compiler built-ins or user defined specialisations, dependent on settings.
Added etl::conditional_t to type_traits.h
Added etl::conjunction and etl::disjunction to type_traits.h
Added etl::integer_sequence to utility.h
Added etl::in_place, etl::in_place_t and etl::in_place_index_t.
Fixed missing etl::alignment_of specialisation for const void.

Allow constexpr etl::delegate_service

Added a specialisation of etl::delegate_service that takes a pointer to a delegate lookup table as a template parameter.

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

By default etl::message derives from etl::imessage.
This option allows it to derive from an alternative, etl::imessage derived class.

Added Arduino examples

20.11.5

Updated Arduino examples

Fixed etl::circular_buffer copy and move assignment bug

Where the destination buffer was not cleared before assignment

Define missing macro when cross compiling with clang for AVR

WCHAR_MIN is not defined when cross compiling with clang for AVR

etl::basic_string::copy is now const

etl::basic_string::copy is now const and does not affect truncation flags.