Broken addresses on command line no longer trigger testnet.

When passing a bitcoin: URI on the command line, invalid addresses do not incorrectly send the
user to the test network.
qt: Remove thousands separators after decimal point

Revert thousands separators after decimal point, as introduced in #4167.
qt: fix tablet crash. closes #4854.

This backports the relevant parts of:
https://codereview.qt-project.org/#/c/82689/
Limit CNode::mapAskFor

Tighten resource constraints on CNode.
Avoid returning many "inv" orphans
Merge pull request #4867

a95b119 qt: Remove thousands separators after decimal point (Wladimir J. van der Laan)
Merge pull request #4874

21f139b qt: fix tablet crash. closes #4854. (Cory Fields)
Move scriptutils.o to wallet
Move CAffectedKeysVisitor to wallet.cpp (remove ExtractAffectedKeys)
Rename scriptutils.o to wallet_ismine.o
Merge pull request #4755

c1e433b Rename scriptutils.o to wallet_ismine.o (jtimon)
8b59a3d Move CAffectedKeysVisitor to wallet.cpp (remove ExtractAffectedKeys) (jtimon)
0d2fa14 Move scriptutils.o to wallet (jtimon)
Merge pull request #4623

e84843c Broken addresses on command line no longer trigger testnet. (Ross Nicoll)
Merge pull request #4878

540ac45 Avoid returning many "inv" orphans (Jeff Garzik)
d4168c8 Limit CNode::mapAskFor (Wladimir J. van der Laan)
Fix crashing bug caused by orphan(s) with duplicate prevout.hash
Headers-first synchronization

Many changes:
* Do not use 'getblocks', but 'getheaders', and use it to build a headers tree.
* Blocks are fetched in parallel from all available outbound peers, using a
  limited moving window. When one peer stalls the movement of the window, it is
  disconnected.
* No more orphan blocks. At all. We only ever request a block for which we have
  verified the headers, and store it to disk immediately. This means that a
  disk-fill attack would require PoW.
* Require protocol version 31800 for every peer (released in december 2010).
* No more syncnode (we sync from everyone we can, though limited to 1 during
  initial *headers* sync).
* Introduce some extra named constants, comments and asserts.

This breaks reindexing, which cannot yet deal with out-of-order blocks on disk.
RPC additions after headers-first
Remove CheckMinWork, as we always know all parent headers
Add CaughtUp() function (needed by later commits)
Improve getheaders (sending) logging
debug "block"