Release 1.3.0 - 28.10.2020

INCOMPATIBLE CHANGES
- SDK Logging API: the log-levels EMERGENCY, ALERT, CRITICAL and NOTICE
  have been removed, leaving only ERROR, WARNING, INFO and DEBUG, to
  offer a simpler and more understandable user experience.
  Simply substitute all mentions of 'log.emergency', 'log.alert',
  'log.critical' with 'log.error', and all mentions of 'log.notice' with
  'log.info' in your code. The same procedure should be followed for the
  dv::logLevels in case you use the dv::Log() API (issue #354).
- SDK Logging API: the formatted logging API has been changed to use
  the fmt library (fmt::format) which uses compatible syntax with C++20's
  std::format; see https://fmt.dev/latest/syntax.html for details.
  The log.level.format(...) API as well as the dv::Log(level, ...) one
  are affected. A new dv:Log() API with no format string has also been
  added, allowing the direct printing of messages (issue #358).
- Cross API: portable_clock_localtime() has been removed. Use fmt::localtime.

NEW FEATURES
- Packaging: support for Ubuntu 20.10 (Groovy) added.
- Calibration: introduced new configuration option "useDefaultFilename"
  (defaults to false), to use a simpler file name for calibration results
  with no ID or date (issue #364).

BUG FIXES
- Core: verify all uses of malloc/free to ensure correct object
  initialization and destruction, move ConfigTree to use new/delete
  (issue #356).
- Systemd service: use absolute paths for all binaries, fixes service
  on older systemd versions that require this.
- TCP Output: first data packet was not sent out to clients (issue #361).