Paper block ordering

[Jay Anderson]

In 2.15.19 the ordering of things in the paper block matters where it
didn't before. An example which removes the first system indent:

============
\version "2.15.19"

\paper
{
  indent = 0\in
  #(set-paper-size "letter")
  %indent = 0\in %Move the indent here to have the indent take effect.
}

\score { \new Staff {R1} }
============

This is a very minor issue (if it is an issue rather than a design
decision going forward), but I figured that it's worth mentioning.

-----Jay