[store points] save multiple positions from UI

[DamKoVosh]

The functions to store points into a python file are added to the UI. For example F2 to create a new file, defining its filename, F3 to store the current robot Pose (entering its name) and F4 key to append a joint pose.

Only implements creation of points; remove, update, delete will be implemented later.

Wouldn't adding two parameters for file name and point name improve the usability a lot? Or will those be added in another PR along the possibility to add multiple points to one file?

Originally posted by @DamKoVosh in #49 (comment)