Add rtpp_log_setlevel() function.
Put few variables under RTPP_DEBUG ifdef.
Make compilable on linux by providing equivalent of kern.hz sysctl
and use CLOCK_MONOTONIC / CLOC_MONOTONIC_RAW instead of
CLOCK_UPTIME_PRECISE.
o Add few new files;

o Make WITHOUT_SIPLOG default;

o add support for RTPP_DEBUG mode;

o add -lrt on linux.
o Fix argument to the rtpp_log_open();

o provide a workaround for missed drand48() prototype on linux;

o hide one variable under ifdef RTPP_DEBUG.
Add couple of "#include <stdint.h>", which is required on linux to get
xintNN_t types.