prim_toPath: Actually make the string a path
nix-prefetch-url: Improve option handling
If hashes do not match, print them in base-32 for SHA-1/SHA-256

Fixes #57.
canonicalizePathMetaData: Fall-back to utimes if lutimes fails due to ENOSYS
Fix "Not an ARRAY reference" error

It's a mystery why this error is not triggered in the build farm
(e.g. http://hydra.nixos.org/build/3265602).  Ah well.
Add an option ‘use-binary-caches’

This allows disabling the use of binary caches, e.g.

  $ nix-build ... --option use-binary-caches false

Note that

  $ nix-build ... --option binary-caches ''

does not disable all binary caches, since the caches defined by
channels will still be used.
nix-push: Handle pushing a symlink
Update nix-push manpage and document the binary cache format
Process binary caches in order of priority

Binary caches can now specify a priority in their nix-cache-info file.
The binary cache substituter checks caches in order of priority.  This
is to ensure that fast, static caches like nixos.org/binary-cache are
processed before slow, dynamic caches like hydra.nixos.org.
download-from-binary-cache: Try next cache if downloading a NAR fails
Update release notes
Use a shorter Nixpkgs channel URL
Remove unnecessary call to closeMostFDs()

We have close-on-exec on all FDs now, and there is no security risk in
passing open FDs to substituters anyway.
Don't start copy-from-other-stores if $NIX_OTHER_STORES is unset

Slight optimisation.
Fix a segfault when auto-calling a "a@{...}" function

Since the called function can return its argument attribute set
(e.g. "a"), the latter should not be allocated on the stack.

Reported by Shea.
Manual: Don't use a store path in our closure

http://hydra.nixos.org/build/3313227
Remove a Darwin hack that should no longer be needed
Remove the quickExit function
Remove some redundant close() calls

They are unnecessary because we set the close-on-exec flag.
Remove definition of non-existant function