Enable use of environment variables in parameters.yaml

[grondman]

Putting this in parmeters.yaml:

globals:
  deploy: $HOME/some_ws/src

leads to the creation of a directory literally called "$HOME", whereas it should be extended to the user's home directory. Enabling the use of environment variables would be nice to have, as it allows for a more generic (default) configuration file for ROL that can be used for more users at the same time.

[grondman]

Same holds for the use of ~

[gadlopes]

I will use this: https://stackoverflow.com/questions/52412297/how-to-replace-environment-variable-value-in-yaml-file-to-be-parsed-using-python