This change introduces a new subtree in the library's directory structure.
Platform-specific code now should be placed into the corresponding directory
in src/platform/. To illustrate this, prng.h has been split into three
distinct files, one for each platform (contiki, lwip, posix) and moved into
the respective subdirectory.
As the libcoap sources have been moved to the sub-directory src it
must be added to the vpath. The header files now reside in include/coap,
so we need an additional -I compiler flag for this.
The root path for libcoap is derived from the variable APPDS which is
set by $(CONTIKI)/Makefile.include. This is a bit fragile but the best
we have...
Olaf Bergmann