Log Message:
Update chicken from 3.10 to 3.20

From Changelog :

- unit extras: moved lists, queues, strings to data-structures
- new unit data-structures
- unit library: symbol->string now copies its argument
- chicken-setup: added option -svn-trunk
- unit utils: added file-copy and file-move (request by the einit team)
- unit srfi-69: added hash-table-clear!
- unit srfi-69: new
- unit extras: moved SRFI 69 to unit srfi-69

Contributed by Aleksej Saushev