Merge branch 'release/0.13.0' into develop
Add draft 1323 (tcp extensions) to README
Setup skeleton for tcp
Implement tcp_prepare with fixed options
Rewrite tcp_prepare, compiled 25% smaller
Implement tcp_send
Fix whitespacing and trailing spaces
Implemented tcp_server_init, tcp_receive, tcp_port_register, tcp_port_unregister
Add reset, syn and fin detection
Calculate tcp checksum over header only
Split tcp_prepare to allow options to be set or not
Introduce add_value_to_buffer

With this you can add a value to a multi-byte number in a buffer.
Boyscout: debug/info_array should pass glue as well
Fix add_to_buffer starting at wrong byte
Add tcp server to network_backbone
Fix window byte size

Four bytes were set, while the window only has two bytes in the
header.
Implement tcp_prepare_reply

This uses construct to set the basic header and swaps the sequence
and acknowledge numbers from the incoming packet. You have to
increase the value of these numbers yourself.
Set initial syn flag outside of construct method.

When using construct to create a reply, you do not want the syn
flag to be set every time.
Implement reply syn request
Implement reply fin request