Install Shellcheck on the testing VM
Add shellcheck checker
Add missing error parser
Add a test case for shellcheck
Fix tags
Do not needlessly disable sh-shellcheck
Update changelog
[Fix #267] Merge branch 'shellcheck'

* shellcheck:
  Update changelog
  Do not needlessly disable sh-shellcheck
  Fix tags
  Add a test case for shellcheck
  Add missing error parser
  Add shellcheck checker
  Install Shellcheck on the testing VM
Rebuild Texi manual