Convert Taverna list of RExpr to R list - v2

This workflow accepts a Taverna list of arbitrary R expressions and returns a single R expression representing an R list containing the original expressions.

This workflow relies on the current Taverna behaviour of an R expression being represented by a list of strings containing the deparsed expression. If this changes, this workflow will likely break.

The first BeanShell converts each R expression (actually a list of strings) to a single string. This uses implicit iteration to do this for each R expression, so input port depth is 2 but the BeanShell input depth is 1.

The second Beanshell creates a comma-separated list of the deparsed R expressions and wraps the string with the R list() function. So now we have a single string s that can be turned into an R list using eval(parse(text=s)).

But RShell already does that parsing for us, so we just need to ensure the string looks like an R expression by turning it into a list of strings. So we actually output a 1-element list containing the string.

Version 1: initial implementation Version 2: reduce number of BeanShells