rework ClientModel::getBlockSource() + BitcoinGUI::setNumBlocks()

- updates ClientModel::getBlockSource() to return all available states and
  sorts enum BlockSource in order of usage cases (none default, then reindex,
  import and network)
- updates BitcoinGUI::setNumBlocks() to better use getBlockSource() and
  also adds a message, when we have NO block source available
Bitcoin-Qt: remove " - " on empty title in BitcoinGUI::message()

- don't display "Bitcoin - " when no title was supplied but just "Bitcoin"
new testnet window .ico file

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>
qt: don't show rpcconnect command line option in help

GUI can't connect to RPC. Showing this option in the help confuses
people, so remove it.
Merge pull request #2514 from TheBlueMatt/master

Add test patches for pull-tester to contrib/
Use a uint256 for bnChainWork

Every block index entry currently requires a separately-allocated
CBigNum. By replacing them with uint256, it's just 32 bytes extra
in CBlockIndex itself.

This should save us a few megabytes in RAM, and less allocation
overhead.
Merge pull request #2513 from laanwj/2013_04_gui_remove_rpcconnect

qt: don't show rpcconnect command line option in help
qt: move export button to tabs

Having the export button at the top was confusing people into thinking
the entire wallet was exported.

This commit moves the export button to the address book, receiving
addresses and transaction tabs separately.
Merge pull request #2418 from sipa/uintwork

Use a uint256 for bnChainWork
Merge pull request #2515 from laanwj/2013_04_move_exportbutton

qt: move export button to tabs
Merge pull request #2492 from Diapolo/Qt_message

Bitcoin-Qt: remove " - " on empty title in BitcoinGUI::message()
Require strictly-standard encodings in mempool
qt: register metatype for bool*

This allows the bool* type to be passed between threads.  Should solve issue #2402.
aboutdialog: use just "The Bitcoin developers" as tr()-string

- this ensures our new splash screen and this will share a translatable
  string an remove the need for an additional translation
bitcoin: use static QApplication:: instead of app.
bitcoingui: remove 2 unneeded includes
overviewpage: make some code Qt5 compatible

- that changes will be fine for Qt4 also
Made it point to 0.8.1
Merge pull request #2527 from patbr0wn/master

Fixed download error
embed bitcoin_testnet.ico in bitcoin-qt.exe (usable for shortcuts)