Reject transactions with excessive numbers of sigops
Simplify and rename CheckWork to ProcessBlockFound
Allow -onlynet=onion to be used

Just an alias for onlynet=tor, but matches the new name
of the proxy option -onion= better.
Add IsReachable(net) function

Allows other parts of the program to query for reachable
status of a network. Similar to IsLimited(net).
Add GetNetworkName function

Returns the network name for an Network enum.
[Qt] move SubstituteFonts() above ToolTipToRichTextFilter

- doesn't belong to the ToolTipToRichTextFilter class so move it up
Add a way to limit deserialized string lengths

and use it for most strings being serialized.
Reduce maximum coinscache size during verification

Due to growing coinsviewcaches, the memory usage with checklevel=3
(and standard settings for dbcache) could be up to 500MiB on a
64-bit system. This is about twice the peak during reindexing,
unnecessarily extending bitcoind's memory envelope.

This commit reduces the maximum total size of the caches used during
verification to just nCoinCacheSize, which should be the limit.
Merge pull request #4603

f0c2915 Simplify and rename CheckWork to ProcessBlockFound (jtimon)
Fix thread name setting

Because of a typo, thread names no longer appeared in the overview.

This was broken in 51ed9ec.
build: check for sys/prctl.h in the proper way

Use AC_CHECK_HEADERS to check for the header, and include it only
if detected and the subsequent HAVE_SYS_PRCTL_H is set.
qt: better looking trayicon

Github-Pull: #4678
Rebased-By: Wladimir J. van der Laan <laanwj@gmail.com>
Merge pull request #4675

ea100c7 Reduce maximum coinscache size during verification (Wladimir J. van der Laan)
Merge pull request #4150

4fad8e6 Reject transactions with excessive numbers of sigops (Peter Todd)
Revert "Reject transactions with excessive numbers of sigops"

This reverts commit 4fad8e6d831729efa1965fa2034e7e51d3d0a1be.
Don't poll showmyip.com, it doesn't exist anymore

Fixes #4679.

This leaves us with only one candidate, checkip.dyndns.org.
GetMyExternalIP should be phased out as soon as possible.
Merge pull request #4682

c33b983 Don't poll showmyip.com, it doesn't exist anymore (Wladimir J. van der Laan)
Reapply: Reject transactions with excessive numbers of sigops

Reverting was based on a misunderstanding, it appears.

Github-Pull: #4150
bitcoin-tx: fix build warnings

Cleans up a bunch of:
warning: missing braces around initializer for ‘const<anonymous struct>’
Merge pull request #4696

616c243 bitcoin-tx: fix build warnings (Cory Fields)