Adding some new commands to the Shell example sketch.

1. Allow lower and uppercase digital/analog pin naming and led as pin name.
2. Extend stty with end of line mode setting.
Improved handling of end of line (input); carriage return and line feed.

1. Update all IOStream::Device drivers that handle new-line; add handling of carriage return.
2. Replace all LF output with CR LF.
3. Remove IOBuffer::gets(); default implementation is fine.
4. IOStream::Device::gets() will handle end of line mode and skip CR in CRLF mode.
5. New end of line mode setting in IOStream::Device; set_eol(mode).
6. Update Trace log strings.