doc: Update more docstrings to have one sentence summary as first line. Reviewed build-aux, libinterp/dldfcn, libinterp/octave-value, libinterp/parse-tree directories. * build-aux/mk-opts.pl, libinterp/dldfcn/__magick_read__.cc, libinterp/dldfcn/amd.cc, libinterp/dldfcn/audiodevinfo.cc, libinterp/dldfcn/audioread.cc, libinterp/dldfcn/ccolamd.cc, libinterp/dldfcn/chol.cc, libinterp/dldfcn/colamd.cc, libinterp/dldfcn/convhulln.cc, libinterp/dldfcn/dmperm.cc, libinterp/dldfcn/fftw.cc, libinterp/dldfcn/qr.cc, libinterp/dldfcn/symbfact.cc, libinterp/dldfcn/symrcm.cc, libinterp/octave-value/ov-base.cc, libinterp/octave-value/ov-bool-mat.cc, libinterp/octave-value/ov-cell.cc, libinterp/octave-value/ov-class.cc, libinterp/octave-value/ov-fcn-handle.cc, libinterp/octave-value/ov-fcn-inline.cc, libinterp/octave-value/ov-java.cc, libinterp/octave-value/ov-null-mat.cc, libinterp/octave-value/ov-oncleanup.cc, libinterp/octave-value/ov-range.cc, libinterp/octave-value/ov-struct.cc, libinterp/octave-value/ov-typeinfo.cc, libinterp/octave-value/ov-usr-fcn.cc, libinterp/octave-value/ov.cc, libinterp/parse-tree/lex.ll, libinterp/parse-tree/oct-parse.in.yy, libinterp/parse-tree/pt-binop.cc, libinterp/parse-tree/pt-eval.cc, libinterp/parse-tree/pt-mat.cc: doc: Update more docstrings to have one sentence summary as first line.

--- a/libinterp/dldfcn/dmperm.cc	Sun May 03 17:00:11 2015 -0700
+++ b/libinterp/dldfcn/dmperm.cc	Sun May 03 21:52:42 2015 -0700
@@ -194,9 +194,10 @@
 @deftypefn {Loadable Function} {@var{p} =} sprank (@var{S})\n\
 @cindex structural rank\n\
 \n\
-Calculate the structural rank of the sparse matrix @var{S}.  Note that\n\
-only the structure of the matrix is used in this calculation based on\n\
-a @nospell{Dulmage-Mendelsohn} permutation to block triangular form.  As\n\
+Calculate the structural rank of the sparse matrix @var{S}.\n\
+\n\
+Note that only the structure of the matrix is used in this calculation based\n\
+on a @nospell{Dulmage-Mendelsohn} permutation to block triangular form.  As\n\
 such the numerical rank of the matrix @var{S} is bounded by\n\
 @code{sprank (@var{S}) >= rank (@var{S})}.  Ignoring floating point errors\n\
 @code{sprank (@var{S}) == rank (@var{S})}.\n\