Merge in heirecka:small-buildsystem-improvements

CMakeLists.txt

deps/CMakeLists.txt

examples/CMakeLists.txt

examples/crypto_bot.cpp

examples/simple_bot.cpp

include/mtx/common.hpp

include/mtx/errors.hpp

include/mtx/events.hpp

include/mtx/events/aliases.hpp

include/mtx/events/avatar.hpp

include/mtx/events/canonical_alias.hpp

include/mtx/events/common.hpp

include/mtx/events/create.hpp

include/mtx/events/encrypted.hpp

include/mtx/events/encryption.hpp

include/mtx/events/guest_access.hpp

include/mtx/events/history_visibility.hpp

include/mtx/events/join_rules.hpp

include/mtx/events/member.hpp

include/mtx/events/messages/audio.hpp