Update the command matcher for the server command to log a more helpful
message when it's called without a subcommand.
Before:
```sh
$ target/debug/grin server
:: Some(ArgMatches { args: {}, subcommand: None, usage: Some("USAGE:\n grin server [OPTIONS] [SUBCOMMAND]") })
```
After:
```sh
$ target/debug/grin server
Subcommand required, use 'grin help server' for details
```
* PoW context is now properly picked depending on the chain type,
edge bits and block height. Height const for T4 hard fork leaving
a couple weeks to have miners in place. Removed now unused Cuckoo context.
* Simplified block siphash
* Fix servers crate compilation
* Tiny bit cleaner block siphash. Maybe.
* Cuckatoo min edge bits update for T4 and mainnet
* Fix header size tests, Cuckatoo31 default means one more bit per edge
* Remove redundant param from verify_size
* block_accepted via adapter is now reorg aware
we skip reconciling the txpool is block is not most work
we skip reconciling the reorg_cache is not a reorg
* rustfmt
* logging tweaks
* rework block_accepted interface
* rustfmt
* rework reorg determination
* introduce BlockStatus to represent next vs reorg vs fork
* rustfmt
* cleanup logging
* log from adapter, even during sync
* default to minimum_confirmation = 10
pass in minimum_confirmations to grin wallet info
* rustfmt
* rebase against master
* fixup wallet tests
* fixup server tests
* remove receive_coinbase fn from wallet to wallet client
* start moving clients into separate mod
* rustfmt
* move wallet client + start listener into wallet 'clients'
* rustfmt
* refactor API to make it more modular and completely decouple sending
* rustfmt
* further decouple API from sending methods
* rustfmt
* remove wallet to wallet client trait
* rustfmt
* rename / refactor client + adapters
* rustfmt
* add adapter concept
* add midding node_clients dir
* add file and null adapters
* rustfmt
* remove receive from owner api
* factor out receiving slates into trait
* rustfmt
* adding listen trait
* rustfmt
* change listener to use trait
* rustfmt
* add test for file-based exchange
* replace http api send command
* rustfmt
* move controller out of libwallet and into top-level wallet dir
* rustfmt
* add moved controller
* First pass at iterative siphash
* Generalizing our siphash24 implementation slightly to make it friendlier to repeated hashing
* Block siphash algorithm, Cuckaroo placeholder
* Cuckaroo validator, still needs to be tested with vectors from the @tromp implementation
* Working cuckaroo validation with test vectors for cuckaroo19, will add cuckaroo29 vectors when a lean or mean implementation can find some solutions
* Update rust version requirement in doc/build.md
* Apply previous updates to doc/build_ES.md
English version was updated and ES version wasn't kept in sync
* headers msg is now "streamed" off the tcp stream
* rustfmt
* cleanup
* move StreamingReader into ser.rs
extract read_exact out into util crate
* rustfmt
* do not treat txhashset.zip download as abusive behavior
* count times, not bytes so we exclude quiet increments
* use inc_quiet when tracking sent bytes via an attachment
* add comment
* fixup "quiet" counter entries
* rustfmt
* use FixedLength to define serialized size in bytes of various structs
replace usages of mem::size_of() with ::LEN so we correctly calculate serialized sizes in bytes
* rustfmt
