Instead of having a huge debug macro that gets expanded every time a
debug print is needed, separate the debugging facilities into
debu.c. This will reduce excess code duplication a lot.
A concept of debugging level is also introduced. This makes it
possible to add debug prints with different priority level and have
some of the prints to be silenced when user is not interested about
them.
Signed-off-by: Timo Kokkonen <timo.t.kokkonen@iki.fi>