update release version

use custom namespace for bundled libfmt (odygrd#315)

* add missing header to file

* rename libfmt namespace and macros

* use custom namespace for bundled libfmt

* use custom namespace for bundled libfmt

* fix tests

fix clang build when QUILL_X86ARCH is defined

fix build

Update BackendWorker.h

update doctest and run CTest in parallel

update doctest and run CTest in parallel

Minor improvements to TimeRotatingFileHandler

report messages via the notificaiton handler

Update README.md

fix some minor compiler warnings in tests