Split MIN_PROTO_VERSION into INIT_PROTO_VERSION and MIN_PEER_PROTO_VERSION

INIT_PROTO_VERSION is the initial version, after a succesful version/verack it is increased to a negotiated version.
MIN_PEER_PROTO_VERSION could be a different value to disconnect from peers older than a specified version.
Make util phexdigit array reusable

class template base_uint had its own private lookup table.
This is saving 256 bytes per instantiation.

The result is not spectacular as bitcoin-qt has only shrinked of
about 1Kb but it is still valid improvement.

Also, I have replaced a for loop with a memset() call.

Made CBigNum::SetHex() use the new HexDigit() function.

Signed-off-by: Olivier Langlois <olivier@olivierlanglois.net>
[Qt] Rework of payment request UI (mainly for insecure pr)

- this shows insecure (unsecured) payment requests in a new yellowish
  colored UI (based on the secure payment request UI) instead of our
  normal payment UI
- allows us to receive paymentACK messages for insecure payment requests
- allows us to handle expirations for insecure payment request
- changed walletmodel, so that all types of payment requests don't touch
  the addressbook
payment-request UI: use SendCoinsRecipient.message for memo
make processPaymentRequest() use a single SendCoinsRecipient

- as one this pulls main purpose is to change a payment request to
  be displayed as a single sendcoins entry
rework an ugly hack in processPaymentRequest()

- use a QStringList to store valid addresses and format them for GUI and
  debug.log usage via .join()
Check integrity of gitian input source tarballs
make -logtimestamps default on and rework help-message
process received messages one at a time without sleeping between messages
Skip comparison tool on win32 since Wine breaks it
Merge pull request #3180 from pstratem/processgetdata

Reduce latency in network processing
No more fHaveGUI

No more specific handling of GUI in bitcoin core.
Replace the last usage of fHaveGUI with a fForceServer
parameter on AppInit2.
Merge pull request #3076 from lano1106/uint256_util

 Make util phexdigit array reusable
Merge pull request #3188 from Diapolo/logtimestamp_def

make -logtimestamps default on and rework help-message
qt: add license header to source files

Closes #839
Make time facet non-constant
Merge pull request #3197 from laanwj/2013_11_qt_license

qt: add license header to source files
Merge pull request #3198 from nvmd/compile_on_mavericks

Make time facet non-constant
Merge pull request #3196 from laanwj/2013_11_nohavegui

No more fHaveGUI
qt: remove unused signal from addresstablemodel