wsegl: waylandwsegl must be a plugin

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
cleanup versioning

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
configure.ac: make pvr2d lib detection work as expected

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>