memaccess.cmake: Cosmetics, whitespace, consistency fixes.

Match the rest of PulseView's CMake file conventions more closely.
memaccess.cmake: Use STATUS instead of WARNING for output.

Using STATUS looks nicer here (and it's an informational message only).

Old:
CMake Warning at CMake/memaccess.cmake:39 (MESSAGE):
  Cross compiling - using portable code for memory access
Call Stack (most recent call first):
  CMakeLists.txt:93 (memaccess_check_unaligned_le)

New:
-- Cross compiling - using portable code for memory access
decode: Fix mixup of bytes vs samples

(DecoderStack::decode_proc): The final argument to srd_session_send()
is a byte count, not a sample count.
(LogicSnapshot::get_samples): Multiply start_sample by the unit size
to get the byte offset into the buffer.
Pass new unit_size argument to srd_inst_probe_set_all()
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