* refactor: initialize libtransmission::Values units in Application::initUnits()
* refactor: use libtransmission::Values instead of Formatter::unitStr()
* refactor: remove Formatter::Size, Formatter:Type
* refactor: use Values::Config to init units in transmission-qt
* refactor: use Values::Config to init units in transmission-mac
* chore: remove unused tr_formatter_foo_init() functions
* chore: make Value::operator+() const
* use Values::Speed, Values::Storage in GTK client
* chore: use snake_case for Formatter methods
* refactor: use Values::Speed in GTK client details dialog
* feat: add Values::Value::is_zero()
* refactor: remove unnecessary UTF8String calls
