window_manager: Escape special chars in window title regex
requested to merge michaelweghorn/accerciser:michaelweghorn/escape_special_chars_in_window_title_regex into master
Escape special characters in the window title when building the regex so they're taken literal rather than having a special meaning in the regex.
This e.g. fixes matching the window title for a Qt Creator
window with a title like
"QtWidget.cxx (vcl/qt5 @ lo) [master] - libreoffice - Qt Creator"
and thus makes highlighting the correct area work when
clicking through the a11y hierarchy in Accerciser when using
the KWinWindowManager on Wayland (enabled via
export ACCERCISER_WINDOW_MANAGER=kwin).