RFE: Add unset

[djerius]

Sometimes you need to delete an environment variable completely (just setting it to the empty string isn't enough). It'd be great if one could do something like:

$config->unset( 'FOO' );

which would translate into unset FOO, ( or unsetenv FOO for csh/tcsh).

[plicease]

Agree, with the caveat that we need to support as well as possible all supported shells. I believe cmd.exe and command.com actually do unset with SET FOO=, (but that is a limitation of those shells) and I am not sure about PowerShell.

[plicease]

https://www.itprotoday.com/powershell/powershell-one-liner-deleting-environment-variables

[plicease]

Implemented in #30

[djerius]

Thanks!