grass.script: Add more parameters to handle_errors

[wenzeslaus]

This add handler, stderr, and env to gs.handle_errors. This allows construction of better exception message and calling g.message with gs.fatal. Otherwise, it follows the same rules as error passed with the explicit kwargs dict parameter. Using stderr and handler to reduce confusion. errors is name of the type of handling in gs.handle_errors, but also the error messages in CalledModuleError.

[echoix]

Is it possible that the new test file isn't run, as the file name doesn't start with test_ or end with _test?

[echoix]

Is it possible that the new test file isn't run, as the file name doesn't start with test_ or end with _test?

Yep, the test wasn't in the list of tests passed or failed.

Also, some conflicts in the docstrings to handle

[echoix]

@wenzeslaus I’m letting you write the commit message and merge

[wenzeslaus]

I just hit the need for this yesterday when working on tests - I got the "g.message not found" message.