ds18b20: rewrite C++ to wrap C, add FTI, update examples

Previously, the C++ and C versions of this driver were separate.  Now
the C++ implementation wraps the C implementation.

In addition, the C++ init() function has been deprecated.  It
currently does nothing, and examples have been modified to remove it's
calls.  This function will be removed in a separate release.

The examples have been further modified to update all detected devices
and print their respective temperatures, instead of only reporting the
on the first device detected.

Signed-off-by: Jon Trulson <jtrulson@ics.com>

src/ds18b20/CMakeLists.txt

@@ -1,9 +1,9 @@
 upm_mixed_module_init (NAME ds18b20
-    DESCRIPTION "Programmable resolution 1-wire digital thermometer"
-    C_HDR ds18b20.h
+    DESCRIPTION "Programmable resolution DS 1-wire digital thermometer"
+    C_HDR ds18b20.h ds18b20_defs.h
     C_SRC ds18b20.c
     CPP_HDR ds18b20.hpp
     CPP_SRC ds18b20.cxx
-#    FTI_SRC ds18b20_fti.c
-#    CPP_WRAPS_C
+    FTI_SRC ds18b20_fti.c
+    CPP_WRAPS_C
     REQUIRES upmc-utilities mraa)