Make CNetAddr::GetHash() return an unsigned val.

This prevents an undefined operation in main.cpp, when shifting the hash value
left by 32 bits.
Shifting a signed int left into the sign bit is undefined in C++11.
Don't overflow signed ints in CBigNum::setint64().

CBigNum::setint64() does 'n <<= 8', where n is of type "long long".

This leads to shifting onto and past the sign bit, which is undefined
behavior in C++11 and can cause problems in the future.
Add test case for CBigNum::setint64().

One of the test cases currently aborts when using gcc's flag -ftrapv, due to
negating an INT64_MIN int64 variable, which is an undefined operation.

This will be fixed in a subsequent commit.
Fix signed subtraction overflow in CBigNum::setint64().

As noticed by sipa (Pieter Wuille), this can happen when CBigNum::setint64() is
called with an integer value of INT64_MIN (-2^63).

When compiled with -ftrapv, the program would crash. Otherwise, it would
execute an undefined operation (although in practice, usually the correct one).
add client startup time as an entry to debug.log (note: logged time in debug.log differs by a few seconds from the one displayed in the Debug window) / make ClientModel::formatClientStartupTime() return a QString
Encapsulate public keys in CPubKey
Refactor: split CKeyID/CScriptID/CTxDestination from CBitcoinAddress

This introduces internal types:
* CKeyID: reference (hash160) of a key
* CScriptID: reference (hash160) of a script
* CTxDestination: a boost::variant of the former two

CBitcoinAddress is retrofitted to be a Base58 encoding of a
CTxDestination. This allows all internal code to only use the
internal types, and only have RPC and GUI depend on the base58 code.

Furthermore, the header dependencies are a lot saner now. base58.h is
at the top (right below rpc and gui) instead of at the bottom. For the
rest: wallet -> script -> keystore -> key. Only keystore still requires
a forward declaration of CScript. Solving that would require splitting
script into two layers.
Added 'immature balance' for miners. Only displayed if the balance is greater than zero.

This adds a field labelled 'Immature' in the overview section under the 'unconfirmed' field, which shows mined
income that has not yet matured (which is currently not displayed anywhere, even though the transactions
exist in the transaction list). To do that I added a 'GetImmatureBalance' method to the wallet, and connected
that through to the GUI as per the 'GetBalance' and 'GetUnconfirmedBalance' methods. I did a small 'no-op'
change to make the code in adjacent functions a little more readable (imo); it was a change I had made in my
repo earlier...but I thought it wouldn't hurt so left it in. Immature balance comes from mined income that is
at least two blocks deep in the chain (same logic as displayed transactions).

My reasoning is:
- as a miner, it's a critical stat I want to see
- as a miner, and taking into account the label 'immature', the uncertainty is pretty clearly implied
- those numbers are already displayed in the transaction list
- this makes the overview numbers add up to what's in the transaction list
- it's not displayed if the immature balance is 0, so won't bother non-miners

I also 'cleaned' the overview UI a little, moving code to the XML and removing HTML.
Testnet, Mark III
Fix issue#1082, testnet difficulty unsigned integer underflow
Add a testnet checkpoint at block 546
Merge pull request #1370 from Diapolo/add_startuptime_to_log

add client startup time as an entry to debug.log
Merge pull request #1357 from sipa/keyid

Refactor: split CKeyID/CScriptID/CTxDestination from CBitcoinAddress
Merge pull request #1392 from gavinandresen/testnet_reset

Testnet reset
incorrect openssl when compared to makefile
Merge pull request #1394 from grimd34th/patch-1

incorrect openssl when compared to makefile
Update bitcoinstrings.cpp
sync english translation master file with current master branch
Merge pull request #1403 from Diapolo/translation_master_file

Translation: sync english translation master file with current master branch (2012-05-31)
Rework network config settings