Qt: new icons

- flat and b/w icons seems to be the new trend
- support for HiDPI/retina
- change icon sizes
- fix assets-attribution.md
- removed unused icons
[Qt] the RPC Console should be a QWidget to make window more independent

- fix issue #5254
Do all block index writes in a batch
Add /opt/local/include/db48 only if it exists.
Move SendMoney() to rpcwallet.cpp.
newlines in strings are invalid JSON

Although script_valid.json and script_invalid.json are loaded correctly by the
JSON interpreter used by bitcoin core, these same files are often used by other
libraries and do not necessarily load correctly due to the fact that newlines
contained inside strings are not valid and must instead use the escape
character \n. The files tx_valid.json and tx_invalid.json handle this
correctly, so I've changed the formatting in script_valid.json and
script_invalid.json to mirror those files.
Use RPC_INVALID_PARAMETER instead of RPC_WALLET_ERROR for invalid amount.
No return at the end of void function.
Disable SSLv3 (in favor of TLS) for the RPC client and server.

TLS is subject to downgrade attacks when SSLv3 is available, and
 SSLv3 has vulnerabilities.

The popular solution is to disable SSLv3. On the web this breaks
 some tiny number of very old clients. While Bitcoin RPC shouldn't
 be exposed to the open Internet, it also shouldn't be exposed to
 really old SSL implementations, so it shouldn't be a major issue
 for us to disable SSLv3.

There is more information on the downgrade attacks and disabling
 SSLv3 at https://disablessl3.com/ .
Format paragraphs properly - count the space between words.
Add a new test for FormatParagraph (string longer than the default width).
[RPC] add rpc-test for http keep-alive (persistent connections)
Make several small string fixes in linearize-data.py

- Add a space after the fixed string prepended to file names when input or
  output file changes
- Clarify the error message when the genesis block is not found in the
  hash list (...why do we have this at all?)
Merge pull request #5435

a26bf47 Add a new test for FormatParagraph (string longer than the default width). (Pavel Janík)
83b81f6 Format paragraphs properly - count the space between words. (Pavel Janík)
Merge pull request #5436

11d7a7d [RPC] add rpc-test for http keep-alive (persistent connections) (Jonas Schnelli)
Remove genesis block hash from error
Merge pull request #5434

683dc40 Disable SSLv3 (in favor of TLS) for the RPC client and server. (Gregory Maxwell)
[Qt] make PaymentServer::ipcParseCommandLine void

- the function only returned true, so make it void
- add a comment about payment request network detection
[Qt] add BIP70/BIP71 constants for all messages and mime types

- also rename current ones to match the new ones
- remove constant from guiconstant.h and add it to paymentserver.cpp
[Qt] ensure socket is set to NULL in PaymentServer::ipcSendCommandLine
[Qt] remove dup lock that is done in SetAddressBook()