Asammdf

Fixes
* fix offsets in mdf4 structures with non-byte members (PR313) thanks to dxpke
* fix issue 317, 318
* fix index error in extract_can method
* fix signal distortions when trimming before plot


Changes
* improve memory usage during sorting
* add option to automatically close ErrorDialog after a timeout

Fixes
* cease explicit propagation of unhandled key combinations to parents
* fixes 310 , 311, 312
* fix can extraction in case of CAN OBD2 messages and ignore_invalid_signals=True
* avoid urllib error in tests
* handle VLSD channels with channel_type Unsigned motorola or unsigned intel


Changes
* persisting last opened file path in QSettings
* connecting 'Ctrl + O' shortcut to Open File
* sync regions in the sub-plots

Fixes:
* fixes 305: drag and drop for computed channels

Fixes
* fix drag and drop for computed channels

Fixes
* fix saving of plot channels

Changes
* improve comparison mode