script for unattended release building

- currently works for FreeBSD and Linux
encapsulate Box struct
support for OSX

- vagrant box is create_dmd_release-osx
- builds 32/64-bit library and 64-bit binaries
support for Windows7

- vagrant box is create_dmd_release-windows
- builds 32/64-bit libraries/tools and a 32-bit dmd binary
enforce exit code == 0
change linux builds to use Debian 6.07

- now 32/64 build on multiarch x86_64