key.cpp: fail with a friendlier message on missing ssl EC support

Previously if bitcoind is linked with an OpenSSL which is compiled
without EC support, this is seen as an assertion failure "pKey !=
NULL" at key.cpp:134, which occurs after several seconds. It is an
esoteric piece of knowledge to interpret this as "oops, I linked
with the wrong OpenSSL", and because of the delay it may not even
be noticed.

The new output is

: OpenSSL appears to lack support for elliptic curve cryptography. For
more information, visit
https://en.bitcoin.it/wiki/OpenSSL_and_EC_Libraries
: Initialization sanity check failed. Bitcoin Core is shutting down.

which occurs immediately after attempted startup.

This also blocks in an InitSanityCheck() function which currently only
checks for EC support but should eventually do more. See #4081.
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.
Add MiningRequiresPeers chain parameter
Add MineBlocksOnDemand chain parameter
Add DefaultMinerThreads chain parameter
Add DefaultCheckMemPool chain parameter
Get rid of RegTest()
Move majority constants to chainparams
Add AllowMinDifficultyBlocks chain parameter
Add RequireStandard chain parameter
Add RPCisTestNet chain parameter
Get rid of TestNet()
Replace virtual methods with static attributes, chainparams.h depends on
protocol.h instead of the other way around
net.h was using std namespace through chainparams.h included in protocol.h
Use Params().NetworkID() instead of TestNet() from the payment protocol
[Qt] Improve rpc console history behavior
[Qt] Remove CENT-fee-rule from coin control completely
Move checkpoint based heuristic checks to AcceptBlockHeader
Get rid of the static chainMostWork (optimization)
Allow ActivateBestChain to release its lock on cs_main