Release 0.14 (2010-02-04)

This release has the following improvements:

The garbage collector now starts deleting garbage much faster than before. It no longer determines liveness of all paths in the store, but does so on demand.
Added a new operation, nix-store --query --roots, that shows the garbage collector roots that directly or indirectly point to the given store paths.
Removed support for converting Berkeley DB-based Nix databases to the new schema.
Removed the --use-atime and --max-atime garbage collector options. They were not very useful in practice.
On Windows, Nix now requires Cygwin 1.7.x.
A few bug fixes.