Asammdf

Changes
* optimizations for string channels
* optimize mdf version 4 RTAB conversion
* support CANape specific partial conversion for mdf version 3
* motorola byte order not supported by mdf version < 3.10

Fixes
* fix append for memory="minimum"
* fix RTABX for mdf version 3
* fix value range to text conversion for mdf version 3
* fix bench script for Python 2.7

Changes
* the major change for this release is the implementation of partial conversions for mdf version 4
* _Signal_ object now hold a real channel conversion object in the _conversion_ attribute
* _ChannelConversion_ object now have a _convert_ method that will apply the conversion rule on a given array
* method _physical_ of _Signal_ objects relies now on the _convert_ method

Changes
* keep master channel name and sync type

Fixes
* fix error in get method when record is not byte aligned (a line was erroneously removed in release 3.0.2)

Fixes
* fix error for big endian types and not byte aligned records

Fixes
* fix mdf3 _prepare_record in case of channels with addition byte offset
* fix algebraic conversion
* improve string channel handling
* fix csv export
* fix appending groups with no samples
* fix cut method when the interval is not found in the measurement
* fix for get method in case of channel with no samples
* fix mdf version3 byte array
* fix mdf version 3 saving of groups without samples with options "minimum" and "low"
* added "physical" method to Signal class
* fix handling of LE strings
* fix appending of CANopen types
* fix handling of channel arrays

The major change for release 3.0.0 is the introduction of chunked group samples access. This enables working with large (GB size files) or atypical files (single group and thousands of channels).

Changes
* chunked data access
* _configure_ package level function was removed
* added _configure_ methods to _MDFx_ classes to configure read and write fragment size
* splitting data on save for mdf version 4 is enabled by default

Fixes
* multiple fixes related to creating _ChannelConversion_ objects
* fix handling of additional byte offset for mdf version 3 channels