Added attribute to pad options in Tcp header
Merged NOP, END, MSS in OptionRFC793
Added TcpOptionUnknown
Added operator== between TcpHeader
Documentation on tcp-header
Revert "Added attribute to pad options in Tcp header"

This reverts commit ab8db4f5e9f9aee00fe76d26e00897537c44ab0a.
Added a CalculateLength method on TcpHeader