Fixed spacing bug (#532)

doc/scapy/introduction.rst

scapy/arch/unix.py

scapy/arch/windows/compatibility.py

scapy/arch/winpcapy.py

scapy/contrib/avs.py

scapy/contrib/cdp.py

scapy/contrib/dtp.py

scapy/contrib/eigrp.py

scapy/contrib/gsm_um.py

scapy/contrib/ikev2.py

scapy/fields.py

scapy/layers/dhcp6.py

scapy/layers/dns.py

scapy/layers/inet6.py

scapy/layers/ntp.py

scapy/layers/snmp.py

scapy/layers/tls/tools.py

scapy/packet.py

scapy/route6.py

scapy/sendrecv.py