update changelog

CHANGELOG.md

@@ -3,9 +3,18 @@
 This project follows semantic versioning.
 
 ### Unpublished
+- `[added]` Usable from rust version 1.13.0. There is now a default feature `nightly`, without which
+  dimensioned does not need a nightly version of the compiler. Note that this makes multiplication
+  and division not work as well, to the point that you can pretty much only use `Dim` with
+  primitives.
+- `[added]` Usable without libstd. There is now a default feature `std`, without which `libcore`
+  will be used. This uses some unstable features.
 - `[added]` Unit conversion example.
-- `[changed]` Removed `Dimensioned` constraint for `D` in `Dim<D, V>`. This enables derived types to work properly. It is a temporary change only until the bug with Rust is fixed. See [issue #6](https://github.com/paholg/dimensioned/issues/6).
-- `[added]` Macro for constructing derived units. The derived block of `make_units!` also now works.
+- `[changed]` Removed `Dimensioned` constraint for `D` in `Dim<D, V>`. This enables derived types
+  to work properly. It is a temporary change only until the bug with Rust is fixed. See
+  [issue #6](https://github.com/paholg/dimensioned/issues/6).
+- `[added]` Macro for constructing derived units. The derived block of `make_units!` also now
+  works.
 
 ### 0.5.0 (2015-12-02)
 - `[added]` This change log!