0.10.0

Added

• MqttProfile: the device's base topic, MqttConfig::baseTopic — the
  namespace under which the suite's convention puts state, config,
  status and set/+, and from which the discovery messages take their
  addresses. Empty means the application's default (effectiveBaseTopic()),
  so a device follows its hostname until a topic is written in. Checked by
  isValidBaseTopic() (ConfigCheck::BadTopic): no wildcard, no leading,
  trailing or doubled /, no control characters, at most MAX_TOPIC_LEN
  (MQTT_PROFILE_MAX_TOPIC_LEN, 64). In the backup as baseTopic
• MqttProfile::getLastBaseTopic() / setLastBaseTopic(): the topic the
  device last announced on, stored beside the settings as device state, so
  that an application can clear the retained messages on the old one after
  the base changed. Not in MqttConfig and not in the backup
• Records written before these fields load with an empty base topic