While doing the checks configure might generate "core" files and will
then try to remove them. Having a "core" directory generates an error
while runing the configure script.
There's no workaround but to rename the core directory.
Moves static state out of Messenger.c and into a Messenger struct
Purely stylistic, no functional changes were made.
This commit also changed all the callers of Messenger as they now have
to pass an instance of the Messenger struct to messenger functions.
Also removed some uses of the 'static' keyword at the beginning of
function definitions when the function was already declared static, as
these caused gcc to whine.
Added crypto to the DHT communications.
This defeats completely the first attack mentioned in
docs/DHT_hardening.
Also updated the build system to build the latest test (it links it with
libsodium)
