* Revised the I2PTunnel client and httpclient connection establishment
throttles. There is now a pool of threads that build the I2PSocket
connections with a default size of 5, configurable via the I2PTunnel
client option 'i2ptunnel.numConnectionBuilders' (if set to 0, it will
not throttle the number of concurrent builders, but will launch a thread
per socket during establishment). In addition, sockets accepted but
not yet allocated to one of the connection builders will be destroyed
after 30 seconds, configurable via 'i2ptunnel.maxWaitTime' (if set to
0, it will wait indefinitely).