Added a new function ProbableBiTwinChainTestFast() for checking BiTwin candidates.

This function checks the numbers in the correct and optimal order.
The function determines the chain length accurately even for short chains unlike the previous implementation.

As a consequence, the primes/h statistics are now fixed.
Primes/h is now about 10% of tests/h, which matches the probability of them being prime.
Linking against boost_timer was missing from makefile.mingw.
Primecoin HP: Fix optimized GetBlockWork() from commit b6a92cd8b9 so that the results match the original code.

The optimized version was incorrectly producing values multiplied by 32^6 compared to the original.
This didn't break anything because every related value was multiplied by the same constant.
Primecoin HP: Use GCC-style builtin functions with Clang.
Added inline assembly for rotate left instruction. Fixes code generated by Clang which failed to produce the rotate instruction.
Allow building without the Qt codec plugins because my MXE build environment lacks them.
Primecoin: Added primeseedtn.muuttuja.org as a new testnet-only DNS seed.
Primecoin HP: Rename the application to Primecoin-HP-Qt on OS X.
Primecoin HP: Updated changes-hp.txt to include recent changes.
Primecoin HP: Documented the new donation feature in changes-hp.txt.
Primecoin HP: Bump version to -hp12.
Merge remote-tracking branch 'primecoin-hp/master'

Conflicts:
	bitcoin-qt.pro
	doc/README.md
	doc/README_windows.txt
	src/net.cpp
	src/version.cpp