This commit adds a C implementation for the DS18B20. The C++
implementation was untouched (ie: it does not wrap the C
implementation). This can be done in the future if desired.
In addition, add an ascii-schematic to both the .h and .hpp files to
better illustrate how to wire up the DS 1-wire interface for the UART.
Signed-off-by: Jon Trulson <jtrulson@ics.com>