Network_type value unused

[ronnno]

relates to #88
relates to #146

network_type (sometimes referred to as network_id) configuration values are unused (reserved value 0 is used for all networks). TBD if to deprecate this field, replace it's implementation or reinstate it as originally intended.

This affects allocation of virtual chain ids. If deprecating this value virtual chain id's uniqueness should be enforced across all deployed Orbs networks.. there is no mechanism to enforce this. what are the implications of having virtual chain name collisions?...