Drop fees by 10x due to the persistently higher exchange rate.

The last fee drop was by 5x (from 50k satoshis to 10k satoshis)
in the 0.8.2 release which was about 6 months ago.

The current fee is (assuming a $500 exchange rate) about 5 dollar
cents. The new fee after this patch is 0.5 cents.

Miners who prefer the higher fees are obviously still able to
use the command line flags to override this setting. Miners who
choose to create smaller blocks will select the highest-fee paying
transactions anyway.

This would hopefully be the last manual adjustment ever required
before floating fees become normal.
Adds additional zero checks for setCompact
 These encoded values should all decode to zero

   Positive Numbers
    0x01003456 (1 byte  0x00)
    0x02000056 (2 bytes 0x0000)
    0x03000000 (3 bytes 0x000000)
    0x04000000 (4 bytes 0x000000_00)

   Negative Numbers
    0x00923456 -(0 bytes, so zero)
    0x01803456 -(1 byte  0x00)
    0x02800056 -(2 bytes 0x0000)
    0x03800000 -(3 bytes 0x000000)
    0x04800000 -(4 bytes 0x000000_00)
Don't store or send side-chain blocks lower than last checkpoint.
small changes to rpc command help message strings
build: Make sure historical release notes end up in distributions

Adds the historical release notes to release tarballs and windows
installers.
Limit the number of orphan blocks

In case the total number of orphan blocks in memory exceeds a limit
(currently set to 750), a random orphan block (which is not
depended on by another orphan block) is dropped. This means it will
need to be downloaded again, but it won't consume memory until then.
[Qt] Fix nTransactionFee in qt-settings
[Qt] Improve single step in bitcoinamountfield
Gitian fixes for 0.9.0rc1 build

- Add 'g++' package (virtualbox images don't have this by default)
- Workaround for determinism in Qt5 resources
- Pass --disable-maintainer-mode --disable-dependency-tracking to
  configure for libqrencode to avoid random errors about missing m4
  directory
- Fix typo -with-pic -> --with-pic

It is not necessary to rebuild dependencies after this commit.
Fixes #3610 and #3612.
added missing homebrew qt dependency on mac osx build documentation.
Merge pull request #3620

65615a3 Gitian fixes for 0.9.0rc1 build (Wladimir J. van der Laan)
Merge pull request #3621 from gubatron/build-osx-qt-dependency-missing

added missing homebrew qt dependency on mac osx build documentation.
Merge pull request #3613 from cozz/cozz1

[Qt] Fix nTransactionFee in qt-settings
Typo fix: `anonimized => anonymized` + `infromation => information`
Merge pull request #3627 from calvintam/fix_typos

Typo fix: `anonimized => anonymized` + `infromation => information`
-Wl,-z,relro and -z,now were wiping out environmental LDFLAGS passed in by the user.
I moved them to HARDENING_* where they belong.
Merge pull request #3634

505867a -Wl,-z,relro and -z,now were wiping out environmental LDFLAGS passed in by the user. I moved them to HARDENING_* where they belong. (Midnight Magic)
gitian: Make linux build of OpenSSL deterministic

OpenSSL was embedding a timestamp causing its build to be
non-deterministic.
Change deps-linux to be deterministic by using FAKETIME
as needed and disabling it when it gets in the way.
gitian: Make linux boost dependency completely deterministic

It appears that the output was different every time.

This doesn't affect the final bitcoind/bitcoin-qt, but is confusing
nevertheless.

Fix it by using FAKETIME and zipping files in deterministic order.
Update the address for downloading libpng

The FTP server what we get libpng from only keeps the latest version in its main folder. Older versions are in the "history" folder. Apparently version 1.6.9 has been released, so 1.6.8 has moved to the history folder.