Update to 3.15.1

changelog:
v3.15.1

This is a small bug fix release:

- Preserve macro hygiene when using code that contains explicit renaming
macros contained within syntax-rules macros. Previously, the syntax-rules
system would not pass renamed variables across to the ER system. So an
identifier could be renamed by syntax-rules but the ER macro would then
have no knowledge of the rename and would be unable to use `rename` to make
the identifier hygienic. For example, the code:

        (let ((unquote 'foo)) `(,'bar))

 Should evaluate to `((unquote (quote bar)))`.

- Added support for multi-line input to `huski`.
- Fixed GHC compiler warnings when building with `-Wall`.