Add save-list

[Kinnardian]

There was a discussion about the best way to accomplish adding save-list with multiple opinions on the arc-lang forum:
http://arclanguage.org/item?id=20834
I thought this was a better place to have a conversation about it.
Original Issue:
Why isn't there a "save-list" function analogous to "save-table"?

[Kinnardian]

#133

[rocketnia]

As I was saying in the thread, I think a good way to go about this is to have Anarki's read do a recursive pass over the Racket read result to convert the immutable hash tables to mutable ones. Then all the code that currently uses save-table can be refactored over time so it uses writefile instead, and save-table can be deleted.

If we want to avoid breaking some Arc users' existing apps, then migrating to writefile could be a bit tricky since it involves changing the file format of the data. File format versioning and migration scripts would be possible ways to help those users.