* geesh/parser.scm (make-parser): Instead of using a nested list for
assignments, use a flat list.
* tests/parser.scm: Adjust existing test for this (which checks a
single assignment) and add a second test which checks multiple
assignments.
* geesh/lexer.scm (get-parameter-expression): Use '#f' to signal an
omitted optional word instead of just omitting the word in the
resulting form.
* tests/lexer.scm: Add a test for omitted optional words.
* geesh/parser.scm: New file.
* tests/parser.scm: New file.
* Makefile.am: Add them.
* .dir-locals.el: New file. Include indenting rules for Shell AST
forms and 'call-with-backquoted-input-port'.