The panic hook prints a backtrace, the panic message, file, and line
number, and a plea to report bugs.

I also tried unrolling the 256-iteration loop further below, but it actually caused a
slowdown (my guess is either branch prediction stopped kicking in or the instruction
cache was being maculated).

* refactor PriceInfo to use Fetch and reuse the client

* forget Fetch future to keep it running in the background

* update Debug message for price_info::Client

* wrap underlying errors in price_info client

* use debug_struct in price_info client debug implementation

* use global fetch service in price_info client

* rename gas_pricer parameter in RunCmd

* move price_info to its own crate

* fix price_info tests

* replace rustc_serialize with serde_json in price_info

* add documentation for price_info

* remove unused rustc-serialize dependency from ethcore

* fix price_info formatting

* re-export fetch crate in price_info

* remove unused cfg attributes in price_info

* add tests for price_info

* whisper skeleton

* basic message store

* rallying and message logic

* pass host info to network protocol handlers

* choose who starts rally based on node key

* module reshuffling

* mining messages

* prune messages by low PoW until below size target

* associated error type for ethkey generators and `OsRng` generator

* beginnings of RPC

* generic message handler for whisper

* reshuffle code order

* standard payload encoding and decoding

* basic crypto

* minor restructuring of net code

* implement shh_post

* merge?

* implement filters

* rand trait for hash types

* filter RPCs for whisper

* symmetric encryption of payload

* pub-sub

* filter tests

* use only secure random IDs

* attach arbitrary protocols to network

* basic integration of whisper into Parity

* eagerly prune low PoW entries

* broadcast messages with salted topics

* node info RPC

* fix import

* fix leading zeros calculation

* address minor grumbles

* split out types into separate crate

* split out evm into its own crate

* Health endpoint.

* Asynchronous health endpoint.

* Configure time api URL via CLI.

* Tests for TimeChecker.

* Health indication on Status page.

* Adding status indication to tab titles.

* Add status to ParityBar.

* Fixing lints.

* Add health status on SyncWarning.

* Fix health URL for embed.

* Nicer messages.

* Fix tests.

* Fixing JS tests.

* NTP time sync (#5956)

* use NTP to check time drift

* update time module documentation

* replace time_api flag with ntp_server

* fix TimeChecker tests

* fix ntp-server flag usage

* hide status tooltip if there's no message to show

* remove TimeProvider trait

* use Cell in FakeNtp test trait

* share fetch client and ntp client cpu pool

* Add documentation to public method.

* Removing peer count from status.

* Remove unknown upgrade status.

* Send two time requests at the time.

* Revert "Send two time requests at the time."

This reverts commit f7b754b1155076a5a5d8fdafa022801fae324452.

* Defer reporting time synchronization issues.

* Fix tests.

* Fix linting.

* RPC cpu pool.

* introduce optional thread pool when processing RPC requests.

* Bump jsonrpc.

* Removing boxes.

* Fix CLI tests.

* lifetime issues

* refactor to new 'native env'

* descriptors and such

* wasm mvp continued

* finalized env/ext bindings

* descriptor -> call_args

* inject gas counter

* result processing and engine activation

* tabify some source files

* needs return new

* wasm tests initial

* erradicate warnings

* origin in the descriptor

* update test repo

* payload verification tests

* identity return payload test

* some test description

* dispersion test

* check length here

* suicidal contract

* engine params

* fix typo

* review fixes

* submodule update

* update - purge reserved space

* doc effort

* more review fixes

* fix error message

* fix dependency url

* reorg error handling

* update submodule

* update utils

* update to latest parity-wasm

* tabify

* fix wasm magic header

* update dependencies

* external create and tests

* update to latest tests

* extra trace info

* Update parity-wasm

* update wasm-utils also

* few traces and result handle change

* alter trace content

* fix issues with optimizer, update to latest parity with validator, etc

* static initialization

* license preamble

* update wasm crates and gas costs

* fix grumbles

* bring back lifetime

* fix compilation

* bigint upgraded to version 3.0

* fixed missing FromHex import in ethcore tests

* fixed missing FromHex import in rpc tests

Fixes build with VS 2017.

This is a huge change, which includes some changes to replace code that
originally cloned to reuse allocations instead. The updated
`elastic-array` crate renames its consuming `Vec`-conversion method to
`into_vec`, which means that I can do a simple
`sed -i 's/to_vec/into_vec/'` and then fix the compilation errors.

This commit is probably a minor performance win and definitely a
significant readability win.