* Adds new `ProvideInherent` trait
Also implements the new trait for `srml/consensus` and `srml/timestamp`.
* Adds `impl_outer_inherent!` macro
* Reexport macros from `alloc`
* Introduce `RuntimeString` and fix `ProvideInherent` on `no_std`
* Replace `VersionString` with `RuntimeString`
* Improvements for `impl_outer_inherent!`
* Make `construct_runtime!` support `impl_outer_inherent!`
* Fixes after rebase
* Whitespace