* gash/pattern.scm (parse-matching-bracket-expression): Do not
report errors until a full bracket expression has been parsed.
* tests/unit/pattern.scm: Add test.
* gash/pattern.scm (string-contains-part-right): New procedure.
(pattern-drop): New procedure.
(pattern-drop-right): New procedure.
* tests/unit/pattern.scm: Test the dropping procedures.
gash/environment.scm: Remove file.
geesh/*: Move these files into the 'gash' folder and replace all
instances of the word 'geesh'.
scripts/geesh.in: Remove file.
HACKING, INSTALL, Makefile.am, configure.ac, guix.scm,
tests/bootstrap/bash-without-bash.scm, tests/spec/Makefile.am,
tests/spec/check-spec, tests/spec/oil.scm, tests/unit/*,
tools/coverage.in: Replace all instances of the word 'geesh'.
Co-authored-by: Jan Nieuwenhuizen <janneke@gnu.org>