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.
[Qt] Improve single step in bitcoinamountfield
Per-peer block download tracking and stalled download detection.

Keep track of which block is being requested (and to be requested) from
each peer, and limit the number of blocks in-flight per peer. In addition,
detect stalled downloads, and disconnect if they persist for too long.

This means blocks are never requested twice, and should eliminate duplicate
downloads during synchronization.
Log warnings when bootstrap files are specified but cannot be opened

- Log a warning when bootstrap files are specified using `-loadblock`
but cannot be opened.
- Log a warning when bootstrap.dat exists in the home directory
but cannot be opened.
linearize.py: Harmonize rpcpass to rpcpassword

linearize.py: harmonize rpcpass to rpcpassword according settings in
bitcoin.conf
fix non-standard reason string in main.cpp
[Qt] allow translation of client bitness
Document new `walletpassphrase` behavior in 0.9

Also add a note to the release notes.
Fixes #3672.
always show syncnode in getpeerinfo (fixes #2717)
remove orphan fHaveGUI from main.h
Serialize only CTransaction data in gettransaction RPC hex

Don't include trailing implementation-specific wallet metadata.
Fixes 3a1c20b.
Merge pull request #3688

7f1b6a6 remove orphan fHaveGUI from main.h (Philip Kaufmann)
Merge pull request #3649

3078b58 linearize.py: Harmonize rpcpass to rpcpassword (Subo1978)
Merge pull request #3643

d54e819 Log warnings when bootstrap files are specified but cannot be opened (Wladimir J. van der Laan)
Merge pull request #3614

b920148 [Qt] Improve single step in bitcoinamountfield (Cozz Lovan)
Merge pull request #3666

bbfce8a fix non-standard reason string in main.cpp (Philip Kaufmann)
Merge pull request #3587

ceb8e22 [Qt] allow translation of client bitness (Philip Kaufmann)
Increase default dbcache to 100 MiB