Automatic DNS Resolver

The current solution supports next features:
- simple subdomain registrar;
- recursive subdomain registrar;
- pure dns resolver (getter; could be run locally);
- recursive dns resolver (with look up request to other dns resolvers and sending result messages to nowhere);
- total register price calculator;
- price list getter;
- method to change owned dns record;
- method to extend expiration time;
- method to withdraw profit (for dns resolver owner);
- scripts to create new resolvers;
- scripts for all supported requests;
- automated testing;
- Docker support.

More information about deployment, testing, and project layout can be found in README.md

Automatic DNS:
+ Automatic forwarding of add/change domain queries.
+ Adds zero to domain name, preventing basic denial of service attacks.
+ Ability to withdraw earnings.
+ Ability to receive donations.
- Price is not calculated recursively for child cells.
- In calc_cost ext_bit_payment and ext_ref_payment used as prices and not as price exponents.
- No garbage collection for expired domains.
- Returns number of bytes instead of number of bits.
- There is no way to change prices after the contract is created.
- Owner check doesn't compare workchain_id.
- Seqno is increased when domain is added.

Price calculation is not correct, it calculates just amount of bits and cell refs in hashmap tree root not accounting value of hashmap leaves and interim cells themselves (which make up most of actual used storage). This way calculated price is way underrated.