Allow labels to be set to empty values
Adjust pv::dialogs::Connect to GVariant-based sr_config_* functions
Adjust pv::SigSession to GVariant-based sr_config_* functions
Adjust pv::toolbars::SamplingBar to GVariant-based sr_config_* functions
Adjust pv:prop::Enum to GVariant-based sr_config_* functions
Make pv::prop objects run on GVariants
Ported pv::prop::binding::DeviceOptions to GVariants
Added Bool property and bound to SR_CONF_RLE
Removed an uneeded include
Added Int property and bound to SR_CONF_CAPTURE_RATIO