Move the Slot* classes to bound_method.{h,cpp} and rename them to
Bound*Method*. They will be reused to implement asynchronous method
invocation similar to cross-thread signal delivery.
This is only a move and rename, no functional changes are included.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>