EnvError should inherit from ValueError

[sacha-sentier]

Hello,

I feel like EnvError should inherit from ValueError instead of the generic Exception.

For instance, env.int of "foo" will raise EnvError, while int("foo") raises ValueError.

It seems to me that both EnvError and ValueError refer to an error inside the value that cannot be safely typecasted. Since ValueError is just a generalization of EnvError, EnvError should inherit from it.

[sloria]

Makes sense. Thanks!