David Mullen

Resolves #38. This implementation probably needs more testing, but at least it does pass the ANSI test suite. As a bonus, this allows the use of `&environment` in `defsetf`, which...

Presumably this is because it was a later addition to ANSI—see [Issue SETF-MULTIPLE-STORE-VARIABLES](https://www.lispworks.com/documentation/HyperSpec/Issues/iss309_w.htm). Also, long-form defsetf is notoriously tricky to implement. For background, see [this SBCL discussion](https://bugs.launchpad.net/sbcl/+bug/1452947).

make-sequence doesn't understand derived types

1

For example: ``` (deftype buffer32 (&optional (size '*)) `(simple-array (unsigned-byte 32) (,size))) ``` Then: ``` > (make-sequence 'buffer32 1024) Debugger called in: #. #: Cannot find the element type in...