Df group (#27)

* Add test file

* Update 8x.FCStd

* Update 8x.FCStd

* Change Vertical for DF

#21

* Update README.md

* Update Horizontal and Vertical

 #21

Code not valid it's just a patch but if the plan is particular it doesn't work
To be reviewed

* Change the correction for the Geometric Tolerance

* Add new group to get a more logical Structure

Add Group DS
and one Groupe by AP

* Update README.md

* Update Icon

Test Missing property

* Update GDT.py

* Change Groupe

* Update Data

test

* update GT

* Update With Limit

* Update GDT.py

* Update

Author: 5axes