Do not use C++11 std::vector.data()

std::vector.data() is a C++11 feature that makes my OSX build machine unhappy.
Use QImage.bits instead of QImage.constBits to ease backporting

Image.constBits was introduced in Qt 4.7.  Should be ok here to use
QImage.bits which allows linking against the Qt in Squeeze.
Merge pull request #2289 from laanwj/201301_qimage_bits

Use QImage.bits instead of QImage.constBits to ease backporting
Add script to clean up datadirs
Some improvements to the release notes
Merge pull request #2297 from sipa/notes

Some improvements to the release notes
Merge pull request #2295 from sipa/tidydir

Add script to clean up datadirs
Merge pull request #2286 from gavinandresen/fix2285

Do not use C++11 std::vector.data()
reformat OS X build instrcs, add 10.8 + Homebrew

* reformatted the entire document to look pretty in both standard text and
  Markdown
* incorporated [my OS X 10.8 build instructions with Homebrew as the package
  manager](http://bitcoin.stackexchange.com/questions/3672/trouble-compiling-bitcoind-on-osx-with-homebrew/5253#5253)
* incorporated @gavinandresen's MacPorts and release build instructions based on
  an earlier revision of this commit
* added makefile patch necessary for Homebrew compilation to `contrib`