Asammdf

Fixes
* copy ranges when copying display properties

Fixes
* fix error when canceling a computation channel dialog

Fixes
* properly close intermediate files in the concatenate and stack methods
* fix drag & drop for numeric window
* fix for wrong channel group info

Changes
* handle already transposed bytes in DZBLOCK

Changes
* added context menu to the plot's channel list selection

Fixes
* fix crashes triggered by selecting the common axis when channels have been removed from the selection list

Fixes
* fixes 248
* fix error when dragging channel groups that contain no channels
* show correct information about the found CAN ID's during extraction
* remove invalid chars from output csv file name
* missing return value in blocks.mdf_v4._load_signal_data (thanks to JulienGrv )


Changes
* _load_data containing invalidation bytes
* improve C extension speed for unsorted mdf v4 files