Asammdf

Fixes
* fix handling of non byte align channels

Announcement
The 4.7 line will be last to support Python version prior to 3.6. From now on only bugfixes will be pushed to it.

Changes
* bring back _\_\_slots\_\__
* ask for cChardet instead of chardet
* minor performance improvements

Fixes
* handle empty channel groups
* do not alter comments (XML content) created by other tools (for example CANape display information)
* disk IO improvements

Fixes
* ensure maximum Matlab variable name for .mat export
* fix handling of CAN bus logging with ErrorFrame and RemoteFrame (issue 108)

Changes
* improve robustness of XML comments parsing
* include offset information for concatenated time basis
* performance improvements
* improve performance of string channels
* optimize channel reading for channels without attachments or default X axis
* improve MDF methods by avoiding copying the master channels


Fixes
* fix typeerror when using numexor evaluate
* fixes in Signal cut

Fixes
* fix big endian handling of channels that have bit offset or non standard size
* fix Signal _cut_ method
* fix MDF _concatenate_ method
* fix benchmark script for new internal package structure
* fixes in plotting
* correctly use np.append when extending Signals

Changes
* add _include_ends_ argument to Signal _cut_ method
* remove _cantools_ and _matplotlib_ from requirements
* add _record_offset_ argument to MDF _select_ and MDF4 _get_ methods
* MDF4 compressed blocks speed optimizations