Remove double-dash parameters from mapArgs

Should be merged after pull request #4281
("Add `-version` option to get just the version #4281"),
because is changed "--help" to "-help".

Checked that grep of 'mapArgs.count("--' returned only
three places that are fixed by pull request #4281.
Ping automatically every 2 minutes (unconditionally)

... instead of after 30 minutes of no sending, for latency measurement
and keep-alive. Also, disconnect if no reply arrives within 20 minutes,
instead of 90 of inactivity (for peers supporting the 'pong' message).
Add `-version` option to get just the version

Adds a `-version` or `--version` option to print just the version
of the program for bitcoind, bitcoin-cli and bitcoin-qt.

Also make it that `-help` can be used to display the help (as well as
existing `--help`). Up to now, `-help` was the only option that didn't
work with either one or two dashes.
util: Add function FormatParagraph to format paragraph to fixed-width

This is to be used for the `-version` and `-help` messages.
remove unused code from getblockchaininfo()
Merge pull request #4328

f379047 remove unused code from getblockchaininfo() (Philip Kaufmann)
Add testnet DNS seed of Alex Kotenko.
Merge pull request #4330

c30329a Add testnet DNS seed of Alex Kotenko. (Andreas Schildbach)
Merge pull request #2784

f1920e8 Ping automatically every 2 minutes (unconditionally) (Pieter Wuille)
Remove -beta suffix

It conflicts with our normal naming of releases/builds. Fixes #4221.
Ignore too-long redeemScripts while loading wallet

This avoids that long redeemScripts that were grandfathered in
prevent the wallet from loading.

Fixes #4313.
Add 'about' information to `-version` output

Adds a copyright and attribution message to the `-version` output
(the same as shown in the About dialog in the GUI).

Move the message to a function LicenseInfo in init.cpp.
qt: Unify AboutDialog and HelpMessageDialog

They share so much code and functionality that they may as well
be one class.
Merge pull request #4281

5c97aae qt: Unify AboutDialog and HelpMessageDialog (Wladimir J. van der Laan)
45615af Add 'about' information to `-version` output (Wladimir J. van der Laan)
97789d3 util: Add function FormatParagraph to format paragraph to fixed-width (Wladimir J. van der Laan)
96b733e Add `-version` option to get just the version (Wladimir J. van der Laan)
Merge pull request #4193

71aaff3 Remove double-dash parameters from mapArgs (Kosta Zertsekel)
Merge pull request #4316

18116b0 Ignore too-long redeemScripts while loading wallet (Wladimir J. van der Laan)
bitcoin-cli, rpcclient: prefer EXIT_FAILURE cstdlib constant

A more complex construction via abs() yields the same end result.

Rebased-From: 34ff109
Rebased-By: Wladimir J. van der Laan <laanwj@gmail.com>
Remove cli functionality from bitcoind

As it says on the tin. It was deprecated in version 0.9, and
at some point it should be removed.

Removes the dependency of bitcoind on libbitcoin-cli.a. Move
some functions that used to be shared but are now only used in
bitcoin-cli.cpp to that file.

After this change, an error is printed (and exit code 1 is returned)
when the user tries to send RPC commands using bitcoind.
Merge pull request #4232

b750cf1 Remove cli functionality from bitcoind (Wladimir J. van der Laan)
remove SOCKS4 support from core and GUI

- now we support SOCKS5 only