better error reporting;
* Added an I2PSocketManager.destroySocketManager() method, that closes all
the managed sockets and destroys the associated I2PSession.
(human)
won't be accepted until the server app actually requires an I2PServerSocket
from the I2PSocketManager.
It allows both to add a little bit of functionality, and to fix a nasty bug: it
was possible to hang an app that connects through the I2PSocketManager but
actually doesn't accept() connections (if 2 connection requests were sent
to the app, the I2PSocketManager got stuck waiting forever on
I2PServerSocketImpl.getNewSocket()).