Adding npz file support

Fixed issues

• MetaData of wv Files: Make some properties public #14
• iqw is read with default meta data #17

New features

• Adding new support for npz files with #18.

Breaking change: File names of the package are now compliant to PEP snake case, e.g. RsWaveform.wv.Load → RsWaveform.wv.load.

Provide additional meta data for WV files

New fields were added:

• reference level as metadata in dictionary
• samples as metadata in dictionary

Initial OSS version

• Support for loading and saving wv, iqtar and iqw files
• Adding some DSP functions for storing meta data