Don't join with non-threads.  Fixes 323
LogicSignal: Un-break trigger configuration. (bug #318)
In View::zoom_one_to_one use View::get_visible_data
Moved DevInst into the pv::device namespace
Added pv::device::Device
Made DeviceManager only handle Device objects
Moved DeviceManager::use_device and release_device into DevInst
Moved DevInst::_sdi down into Device
Moved SigSession::is_trigger_enabled into DevInst
Removed a redundant call to SigSession::set_device
Moved session creation into DevInst objects
Moved default device functionality into SigSession
SamplingBar: Surpressed a spurious update loop
Show the file-device in the selector when a file is loaded
Don't attempt to set SR_CONF_LIMIT_SAMPLES when it's not supported
Use boost::filesystem::path to get the filename from a path
SamplingBar: Only use DefaultSampleCount if the _sample_count widget is unset.

This fixes bug #324
Added LogicSignal::get_data
Added a reference to the SigSession in DecoderStack
Begin a new decode session when a new frame begins