Feature request: support for interpolation

[GigiusB]

It would be nice if interpolation was supported

Example:

MY_FIREWALL=10.10.0.1
MY_FRONTEND=192.168.10.1
MY_BACKEND=192.168.10.1
MY_HOSTS="${MY_FIREWALL},${MY_FRONTEND},${MY_BACKEND}"

should give:

$ echo $MY_HOSTS
10.10.0.1,192.168.10.1,192.168.10.1

[ashald]

Don't we have this already as a feature toggle? https://github.com/ashald/EnvFile#usage