Log Message:
Update to 3.17

ChangeLog:
v3.17
--------

- Added support for \ 
[`define-record-type`](http://justinethier.github.io/husk-scheme/manual/node57.html) \ 
from R<sup>7</sup>RS and SRFI 9. This syntax allows creation of new \ 
disjoint types supporting access to multiple fields.
- Added support for parameter objects from R<sup>7</sup>RS and SRFI \ 
39. See [dynamic \ 
bindings](http://justinethier.github.io/husk-scheme/manual/node41.html) in the \ 
user manual for more information.
- Added a `(scheme process-context)` library containing the following functions:
     - \ 
[`emergency-exit`](http://justinethier.github.io/husk-scheme/manual/node86.html#emergency-exit)
     - \ 
[`exit-fail`](http://justinethier.github.io/husk-scheme/manual/node86.html#exit-fail)
     - \ 
[`exit-success`](http://justinethier.github.io/husk-scheme/manual/node86.html#exit-success)
     - \ 
[`get-environment-variable`](http://justinethier.github.io/husk-scheme/manual/node86.html#get-environment-variable)
     - \ 
[`get-environment-variables`](http://justinethier.github.io/husk-scheme/manual/node86.html#get-environment-variables)
     - \ 
[`system`](http://justinethier.github.io/husk-scheme/manual/node86.html#system)

Bug Fixes:

- Fixed a macro bug where the last element of a pattern's improper list may not \ 
be matched correctly if there is an ellipsis earlier in the list.
- Prevent infinite recursion when evaluating a pointer that contains a pointer \ 
to itself.
- Fixed the compiler to add full support for splicing of `begin` definitions.
- Updated `dynamic-wind` to return the value from the `during` thunk instead of \ 
the `after` thunk.