Release v.0.9.1 GLI 2021 fixes

Two major fixes vor GLI 2021 are provied; wrong formula application and one wrong number in the coefficient tables.

Release v.0.9.0: Historical and Asian Equations, first classifiers

Full feature freeze for version 1.0.

Adding massive amount of new reference equations, mostly historical and Asian modules.
Full feature list is available in the README.md file.

v.0.3.7 fix for Bowerman equations

0.3.7

Release 0.3.6 with SCAPIS 2023

Now SCAPIS lung function reference equations (DOI 10.1164/rccm.202212-2341OC ) are included.

v.0.3.3

Relase of version v.0.3.3 containing more functions from different papers and some fixes.

v.0.2.0

First release candidate with Kuster 2008, GLI 2012 and GLI 2017 spirometry equations