Merge changes from PR #47 related to windows platform support.
Add full windows platform support including correct error checking and working regression tests and examples.
Remove need to build applications using libcoap with -DWITH_POSIX and to include coap_config.h. This applies to the examples as well.
coap_malloc_type() and coap_free_type() provide an abstract API for
dynamic memory management on different platforms. resource.c still
is in transition and needs more cleanup.
In preparation for changing the make buildsystem to a fully autotools
controlled system moving the core libcoap source files to a better logical
place.
All the library related header files moving to include/coap/ to get
all the public and local header files in a separate place. Also moving
the C source files of the libcoap library to the folder src/.