Release 0.6.7-1 to Debian experimental.
Drop workaround for missing hashbytes function

Use correct archives and linker flags to include the HashBytes function built
into XULRunner.

Kudos to megaloni.

Fixes #12.
Merge branch 'master' into debian
xpcom_abi:get return values with NS_ERROR_GET_CODE

Since Gecko 19, the type "nsresult" is not an integer, but an enum class.
This causes compiler errors when returning the nsresult from a function.

By wrapping nsresult in the NS_ERROR_GET_CODE() macro, we can retrieve the numerical value of the error code.
Since Debian testing still has 10.0 (without mozglue) we need to conditionally compile for it.
Merge branch 'master' into debian
Build against xulrunner 19 and update changelog.