Release 1.3 (2013-01-04)

This is primarily a bug fix release. When this version is first run on Linux, it removes any immutable bits from the Nix store and increases the schema version of the Nix store. (The previous release removed support for setting the immutable bit; this release clears any remaining immutable bits to make certain operations more efficient.)

This release has contributions from Eelco Dolstra and Stuart Pernsteiner.