UPD: Documentation update, including warning about backwards compatibility

[skip ci]
Merge branch 'develop'

Conflicts:
	README.rst
Merge branch 'develop'
UPD: changelog and version

Release number pushed to v0.1.3 for hotfixes, and changelog updated to include fixes.
REF: Moved load_file from Data class to separate method

load method now creates a data class and supports 'auto' detection of filetype.

Also some basic refactoring to reduce line lengths.

Tests and docs updated to reflect changes.
ADD: Load and save methods

Added load and save methods to create Data object from file or list of files.

Includes auto-detect data type.
Fixed docstrings.
Removed load_file from Data class definition.