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)
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.
Wallet locking fixes for -DDEBUG_LOCKORDER

Compiling with -DDEBUG_LOCKORDER and running the qa/rpc-test/ regression
tests uncovered a couple of wallet methods that should (but didn't)
acquire the cs_wallet mutext.

I also changed the AssertLockHeld() routine print to stderr and
abort, instead of printing to debug.log and then assert()'ing.
It is annoying to look in debug.log to find out which
AssertLockHeld is failing.
Display progress of rescan.
Add progress to initial display of latest block downloaded.
add test of DecodeBase58 skipping whitespace
script: tighten multisig non-standard rules: do not relay pubkeys above 65 bytes
Get rid of C99 PRI?64 usage in source files

Amend to d5f1e72. It turns out that BerkelyDB was including inttypes.h
indirectly, so we cannot fix this with just macros.

Trivial commit: apply the following script to all .cpp and .h files:

    # Middle
    sed -i 's/"PRIx64"/x/g' "$1"
    sed -i 's/"PRIu64"/u/g' "$1"
    sed -i 's/"PRId64"/d/g' "$1"
    # Initial
    sed -i 's/PRIx64"/"x/g' "$1"
    sed -i 's/PRIu64"/"u/g' "$1"
    sed -i 's/PRId64"/"d/g' "$1"
    # Trailing
    sed -i 's/"PRIx64/x"/g' "$1"
    sed -i 's/"PRIu64/u"/g' "$1"
    sed -i 's/"PRId64/d"/g' "$1"

After this commit, `git grep` for PRI.64 should turn up nothing except
the defines in util.h.
Remove definition of PRI?64 in util.h

This was a bad idea. This can't be solved with macros as any
other library that includes inttypes.h will get in the way.

The parent commit has removed all usages from the source, this commit
removes the definition.
Merge pull request #3718 from jgarzik/pubkey-size

script: tighten multisig non-standard rules: do not relay pubkeys above 65 bytes
Test for walletbackup/walletdump RPC calls
Merge pull request #3700 from gavinandresen/backuptest

Test for walletbackup/walletdump RPC calls
Merge pull request #3305 from mikehearn/fee_drop

Drop fees by 10x due to the persistently higher exchange rate.
Merge pull request #3704 from gavinandresen/wallet_lock_fixes

Wallet locking fixes for -DDEBUG_LOCKORDER
gitian: Make protobuf win32 intermediate output deterministic

While building protobuf in different environments we noticed that
the host tool protoc was slightly different between builds (a symbol table
sorting issue).
Add a deterministic seed as well as disable zlib support.

Exected output is now:

    e2e403e1a08869c7eed4d4293bce13d51ec6a63592918b90ae215a0eceb44cb4 protobuf-win32-2.5.0-gitian-r4.zip
    a0999037e8b0ef9ade13efd88fee261ba401f5ca910068b7e0cd3262ba667db0 protobuf-win64-2.5.0-gitian-r4.zip

No effect on final executables so no version bump.
Document that CPubKey.IsValid() is consensus critical
Merge pull request #3712

a3138ed add test of DecodeBase58 skipping whitespace (Christian von Roques)
Merge pull request #3559

e6c6bc9 Adds additional zero checks for setCompact  These encoded values should all decode to zero (Noel Tiernan)
Merge pull request #3742 from laanwj/2014_02_win32_protobuf_determinism

gitian: Make protobuf win32 intermediate output deterministic