Modified to better suit Curv's use case.

[shlomishamir]

• Bug fixes, e.g.
  • disallow undeclared fields (were ignored)
  • disallow missing fields (were getting empty values)
  • enforce predefined type of domain fields (was allowing the user to define the types)
  • several other cases where invalid messages were accepted
• Structs are now immutable (which simplifies things), must be fully initialized on creation.
• Removed support for default-domain
• Removed ConsenSys-specific tests

[shlomishamir]

accidental