* Removed tne preprocessor defines for coap_tick() and coap_clock_init() --
this made the code less readable and seemed to be of little use.
* Introduced the new type coap_time_t to represent wall clock time. On POSIX,
this is the number of seconds since the epoch, while on embedded systems
without a real time clock, this could be the number of seconds since the
last reboot. The new function coap_ticks_to_rt() is used to convert
coap_tick_t to coap_time.h. Currently, this is a division by COAP_TICKS_PER_SECOND
on all platforms.
* POSIX: coap_tick_t is now defined as unsigned long to avoid overflows in
coap_ticks().
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/.