[wip] Feature/implement missing operations

[xeroc]

The following operations are missing:

• [ ] Operation fill_order missing!
• [ ] Operation account_transfer missing!
• [ ] Operation witness_create missing!
• [ ] Operation proposal_delete missing!
• [ ] Operation withdraw_permission_update missing!
• [ ] Operation withdraw_permission_claim missing!
• [ ] Operation withdraw_permission_delete missing!
• [ ] Operation committee_member_update missing!
• [ ] Operation committee_member_update_global_parameters missing!
• [ ] Operation vesting_balance_create missing!
• [ ] Operation transfer_to_blind missing!
• [ ] Operation blind_transfer missing!
• [ ] Operation transfer_from_blind missing!
• [ ] Operation asset_settle_cancel missing!
• [ ] Operation fba_distribute missing!
• [ ] Operation execute_bid missing!
• [ ] Operation htlc_redeemed missing!
• [ ] Operation htlc_refund missing!
• [ ] Operation custom_authority_create_operation missing!
• [ ] Operation custom_authority_update_operation missing!
• [ ] Operation custom_authority_delete_operation missing!

A few of which are quite tough to implement:

• committee_member_update_global_parameters
• transfer_to_blind
• transfer_from_blind
• blind_transfer

Others seem to be virtual operations (correct me if I am wrong @abitmore):

• fill_order
• asset_settle_cancel
• fba_distribute
• htlc_redeemed
• htlc_refund

[xeroc]

Except for the confidential transactions, the operations themselves are now implemented.

I still need to implemented

• ChainParameters
• CestingPolicy
• Custom Authority: Restrictions

in objects.py

[xeroc]

I got most operations and types implemented (unittests missing still).

However, I ran into the uglyness of custom_authority restrictions and how it uses arguments. Its doable in python but will produce alot of boiler plate code due to the way how types are used/defined in python.

This will take me more time than anticipated.

[xeroc]

I decided to make the custom authority operation a separate issue so this doesn't turn into a super-epic.