scripts/parser: parse_cstyle_call: fix escaping in case of no argument.
scripts/parser: build_cstyle_call: escape parentheses.
scripts/shell.utils: stage_lister_directory: fix quoting in call of subsession runner.

...taking into account that ${STAGE_LISTER[@]} and ${TYPE_PARSER[@]} are already
quoted eval-ready.
Also we now use build_cstyle_call for both arguments.
scripts/shell: drop selective stage list.

It was an uber-user-unfriendly thing. The adequate replacement functionality
will be re-added as a possibility to amend the stage list in $EDITOR (yaourt-
style TODO list editing).
scripts/shell: runner: (hopefully) improve error handling of the invoked command.

This is intended to catch Ctrl+C properly as well.
scripts/shell: improve debug (use single quotes).
scripts/urlops: add functions for URL escaping operations (rawurlencode and rawurldecode).
scripts/shell.utils: stage_lister_directory: do not inherit stage lister for subsession calls on directories.

The inherited stage lister may be specialized, thus unsuitable for directories.
Instead, use a special variable ${STAGE_LISTER_DIRECTORY}, defaulting to
stage_lister_directory.