Change signal/app::draw order in emitSignal().

Puts both signals adjacent to each other for reading, moves the
pseudo-deprecated app::draw() out from in-between them.
Intent is not to use app::draw(), so in case someone is dipping
their toes in the SignalDraw, this prevents it from being overdrawn
by the virtual method.
Added nextUint range convenience methods.

Parallels the nextInt methods.