Major protocol changes, this commit breaks all network compatibility.

Removed a bunch of useless space from various structs.

pack_nodes() and unpack_nodes() are now used to transmit lists of
nodes for the DHT and onion parts. They provide a way to transmit
both ipv6 and ipv4 nodes in the same packet in a portable way that
takes as little space as possible without compression.

Using pack_nodes, merged the send nodes and send nodes ipv6 packets
into one packet greatly reducing the risk of amplification attacks.
Fixed regression, announce responses can contain 0 nodes.
DHT_bootstrap.c now has TCP server functionality enabled.

Fixed a regression (same type as last commit).
multiple spelling fixes
Some speedups and small fixes.
Merge pull request #834 from cgar/spelling

multiple spelling fixes
Fixed build issues.
Added function to increment nonce by specified number.

Nonces now behave like big endian numbers.
Added text document explaining what needs to be done before TCP can be merged.
Fixed possible pointer issues.
Autoconf apparently gives us a nice define for processor endianess.
Fixed possible buffer overflow in function to send friend requests.
Small cleanups.
Removed deprecated function from public api.

Added upper length check to friendreq_handlepacket().
Small cleanup.
Crypto related cleanups.

Moved Bunch of functions from net_crypto to crypto_core.

decrypt_data_fast and decrypt_data_symmetric were the same thing
therefore, removed decrypt_data_fast.

Replaced all the crypto_secretbox_* defines with the equivalent
crypto_box_* one.

New define: crypto_box_KEYBYTES that is equal to
crypto_box_BEFORENMBYTES.
Fixed a test.

Removed function from Messenger.h
Fixed test.
Decided pretty much how the handshake would work.

Started writing the code.

Astyled some files.
Major cleanups.

Fixed circular dependency between DHT and net_crypto: DHT no longer
depends on net_crypto.

Moved the crypto request packets functions to crypto core and DHT.

Cleaned up/added some defines that can be used to get the true maximum
length of things like the friends request message.

MAX_DATA_SIZE has been replaced in most places by more appropriate defines.