added instrcutions for editing FlexibleSUSY.m to make it useful for the NMSSM.
minor changes to instructions for nmssm in paper.tex.
typo fix on last line in paper.tex.
always write out MINPAR and EXTPAR blocks

There might be cases where not all blocks and or parameters are given.
In this case it's important to write out the used values of the
unspecified parameters to avoid confusion.
always write out SMINPUTS block