Give warning when non-default env file can't be found

[barspi]

If an explicit env file and/or dir are set on the Q2 command line (options -E and -Ed ), maybe a WARNING should be given by Q2 if the file can't be found (or read). Maybe even an ERROR :-)

If things are left at their default values (i.e. default environment to be found under cfg ), then it's admissible to show no warning, as this file is optional.

[ar]

Looks good to me. PR?

[barspi]

What do you think the right approach should be?

• WARNING printed by Q2 when it starts, but merrily go on
• ERROR making Q2 fail altogether

(again, only for cases when an explicit environment file and/or path have been given, different from cfg/default)

[ar]

I'd start with a WARNING, see how it looks, then we may choose to ERROR and exit.