Parallel installable checklist

An unsorted list of things we need to rename for parallel installable versions:

• pkgconfig file
• header location (/usr/include/gtk-3.0)
• docs location (/usr/share/gtk-doc/html/gtk3)
• themes location (/usr/share/themes/$NAME/gtk-3.0)
• data location (/usr/share/gtk-3.0)
• library soname
• introspection typelibs
• module location (/usr/lib64/gtk-3.0/3.0.0)
• installed binaries: gtk3-demo, gtk3-widget-factory, gtk3-icon-factory, gtk-query-immodules-3.0
• gettext domain
• autoconf macros