[Qt] fix style, formating, comment and indentation problems

- introduced by #3920
Merge pull request #3923

cfe4cad [Qt] fix style, formating, comment and indentation problems (Philip Kaufmann)
Merge pull request #3619

7398f4a improve command-line options output (Cozz Lovan)
Merge pull request #3682

3e0753b always show syncnode in getpeerinfo (fixes #2717) (Philip Kaufmann)
Merge pull request #3603

a486abd replace custom GetFilesize() with boost::filesystem::file_size() (Philip Kaufmann)
add constant for shared (GUI/core) -par settings

- introduce DEFAULT_SCRIPTCHECK_THREADS in main.h
- only show values from -"MAX_HW_THREADS" up to 16 for -par, as it
  makes no sense to try to leave more "cores free" than the system
  supports anyway
- use the new constant in optionsdialog and remove defaults from
  .ui file
'sendrawtransaction' improvements

- Make it report the reject code and reason
- Make it possible to re-send transactions that are already in the mempool
Merge pull request #3698

5409404 add constant for shared (GUI/core) -par settings (Philip Kaufmann)
Merge pull request #3730

1d46fe3 'sendrawtransaction' improvements (Wladimir J. van der Laan)
remove an assignment which is never used.
Make GetAvailableCredit run GetHash() only once per transaction.

This makes the first getbalance/getinfo 63x faster on my wallet.
Merge pull request #3922

c17f0a5 [Qt] remove space from translation of client bitness (Philip Kaufmann)
Merge pull request #3973

a60ab0b Make GetAvailableCredit run GetHash() only once per transaction. (Gregory Maxwell)
Add nHighTransactionFeeWarning as per #3969.
Fix `-printblocktree` output

PrintBlockTree output was broken starting from e010af70.
Everything appears on one line.

PrintWallet() added the newline after a block, but this functionality
was removed and no newline was added.

Seemingly, no one noticed. Add a newline after the block information
to fix this.
Merge pull request #3875

89d72f3 Add new DNS seed from bitnodes.io. (Addy Yeow)
Add Andreas Schildbach to gitian download scripts.
Remove weights from download config for now as it's unclear how it will be used in future.
Merge pull request #3907 from schildbach/gitian-downloader-aschildbach-key

Add Andreas Schildbach to gitian download scripts.
Merge pull request #3980

af4c2ac Fix `-printblocktree` output (Wladimir J. van der Laan)