Lambda sections do not honor current delimiters

[agentgt]

When used as the data value for an Interpolation tag, the lambda MUST be
treatable as an arity 0 function, and invoked as such. The returned value
MUST be rendered against the default delimiters, then interpolated in place
of the lambda.

When used as the data value for a Section tag, the lambda MUST be treatable
as an arity 1 function, and invoked as such (passing a String containing the
unprocessed section contents). The returned value MUST be rendered against
the current delimiters, then interpolated in place of the section.

I believe this is an easy fix as I just accidentally assumed arity 0 rules but what is more desirable is to get the lambda spec tests to run.