Make 'options(error = function(e) traceback(2))` optional in testJob

[mb706]

I would like to run testJob() and drop to the debugger as soon as an error is thrown. However, the following prevents me from just having options(error=recover) do its work:

batchtools/R/execJob.R

Lines 50 to 51 in 4c2a476

	options(error = function(e) traceback(2L))
	on.exit(options(opts))

Maybe you could make this line dependent on some setting, e.g. have an option(error.execjob) or something (default function(e) traceback(2L)) and then do

options(error = getOption("error.execjob", function(e) traceback(2L)))

(btw, it would probably also be cleaner to have the on.exi() happen before the options(error = ...) call).