Asammdf

Fixes
* multiple fixes to handling of CAN bus logging measurements
* don't ignore channels argument in to_dataframe method
* fix to_dataframe in case of channels with invalidation bits
* export fixes for mat and hdf5
* do not read samples two times in export method for "parquet" or "single_time_base=True"
* fix get method for channel composition when the fields have conversion rules

Changes
* added sub-plots to GUI
* updated GUI documentation
* multiple enhancements to GUI
* add method to extract all raw can signals from anonymous can bus logging
* added validate method to Signal that will apply the invalidation_bits
* reduce memory usage for to_dataframe by converting float64 channel to float32 and checking the minimum dtype that can represent all samples for integer channels
* add compression option to export
* improve performance for channels with invalidation bits

Fixes
* fixes issues 143, 146, 147, 148 and 149
* handle CAN bus logging were the channel group source comment is empty

Changes
* CTRL+C to copy channel name from display list
* increase search dialog size
* remove font color for selection list items
* bring back range editor
* accept file drag and drop in GUI

fixes
* don't close or hide Datalyser

Fixes
* fixes issues 144, 142, 145

Changes
* use natural sorting in GUI (requires natsort)

Fixes
* fixes 136, 137 , 138, 139, 140
* fix error in mdf v4 RTABX conversion parsing
* merged 141 (thanks to JulienGrv )
* fix for CAN bus logging when CAN messages were not found in the attached database
* fix for CAN bus logging when the attached database is not found (external attachment)

Changes
* related to 137
* important speed and RAM improvements for the _select_ method
* added _copy_master_ argument to _select_ method

Fixes
* fixes issue 133

Changes
* implements issue 101
* added _raw_ argument to _select_ method
* accept file like object as destination for _save_ method