Native Bluetooth support for Linux and/or Windows

by Claudiu for Subsurface

Currently Subsurface and libdivecomputer uses the RFCOMM emulation to communicate with Bluetooth dive computers. The scope of the project is to replace this communication with a native one or with one which uses the Bluetooth module offered by Qt framework. In the end the user will no longer have to setup the virtual serial ports and will be able to discover and connect to dive computers which have support for Bluetooth.