* gash/environment.scm: New file.
* build-aux/build-guile.sh (SCM_FILES): Add it.
* gash/peg.scm: Include it.
(assignment, %global-variables, set-shell-opt!, variable): Remove.
* gash/config.scm.in:
* configure: Use it to generate gash/config.scm
* .gitignore: Ignore generated file.
* gash/gash.scm (display-version): Use it.
* build-aux/build-guile.sh: Compile it.
* AUTHORS: New file.
* gash/bournish-commands.scm: New file. Imported and adapted from GNU
Guix.
* gash/bournish-commands.scm: Likewise.
* gash/gash.scm (%commands): Add commands from Bournish.