WIP done(ish). Reorganise input system

WIP done(ish). Reorganise input system
Split Remote (base class) / RemoteWin / RemoteLinux(inc CEC) /
 (defunct) RemoteLirc into separate classes
Replace with: InputLinux, InputCEC, InputUDP, InputWin, (InputLirc)
And InputMan to manage them all.
Move UDP class into Input system
Now any combination of input modules can be active.
Added pipe-quit wait style to DSock
Switch InputUDP to std::thread
Move static strings functions to InputMan.
Split translist into individual Input classes.
Remove all old/new remote stuff - has never been active on RPi.
Drop libcec3 support