Asammdf

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

Fixes
* fixes issue 133
* fixes issue 132
* open files using mmap in read-only mode

Changes
* use period keyboard button to set curve dots in GUI