Easy change: make Stream::timedRead() public

Reading a few bytes from a serial port with a timeout is a pretty basic thing, and right now you have to set up a buffer and call Stream::readBytes() with a pointer to do it.

If you made Stream::timedRead public then it would simplify things. It would be easy: all you would need to do is change a few lines in Stream.h.

Here is some sample code from my company that would be simpler if we were able to use timedRead():

We defined our own function called readByte() which does exactly what timedRead() does because we wanted that functionality. If you just made timedRead() public we could get rid of that function and use timedRead instead. I expect lots of people could benefit from this.