doc: Update more docstrings to have one sentence summary as first line. Reviewed optimization, polynomial, signal script directories. * scripts/optimization/fminbnd.m, scripts/optimization/fminsearch.m, scripts/optimization/fminunc.m, scripts/optimization/fsolve.m, scripts/optimization/fzero.m, scripts/optimization/glpk.m, scripts/optimization/lsqnonneg.m, scripts/optimization/pqpnonneg.m, scripts/optimization/qp.m, scripts/optimization/sqp.m, scripts/polynomial/compan.m, scripts/polynomial/mkpp.m, scripts/polynomial/mpoles.m, scripts/polynomial/pchip.m, scripts/polynomial/poly.m, scripts/polynomial/polyaffine.m, scripts/polynomial/polyder.m, scripts/polynomial/polyeig.m, scripts/polynomial/polyfit.m, scripts/polynomial/polygcd.m, scripts/polynomial/polyint.m, scripts/polynomial/polyout.m, scripts/polynomial/polyval.m, scripts/polynomial/ppder.m, scripts/polynomial/ppint.m, scripts/polynomial/ppjumps.m, scripts/polynomial/ppval.m, scripts/polynomial/residue.m, scripts/polynomial/roots.m, scripts/polynomial/spline.m, scripts/polynomial/splinefit.m, scripts/polynomial/unmkpp.m, scripts/signal/arch_fit.m, scripts/signal/arch_rnd.m, scripts/signal/arma_rnd.m, scripts/signal/autoreg_matrix.m, scripts/signal/bartlett.m, scripts/signal/blackman.m, scripts/signal/detrend.m, scripts/signal/diffpara.m, scripts/signal/durbinlevinson.m, scripts/signal/fftconv.m, scripts/signal/fftfilt.m, scripts/signal/fftshift.m, scripts/signal/filter2.m, scripts/signal/freqz.m, scripts/signal/hamming.m, scripts/signal/hanning.m, scripts/signal/hurst.m, scripts/signal/ifftshift.m, scripts/signal/periodogram.m, scripts/signal/sinc.m, scripts/signal/sinetone.m, scripts/signal/sinewave.m, scripts/signal/spectral_adf.m, scripts/signal/spectral_xdf.m, scripts/signal/spencer.m, scripts/signal/stft.m, scripts/signal/synthesis.m, scripts/signal/unwrap.m, scripts/signal/yulewalker.m: Update more docstrings to have one sentence summary as first line.

--- a/scripts/optimization/lsqnonneg.m	Mon May 04 14:22:02 2015 -0700
+++ b/scripts/optimization/lsqnonneg.m	Mon May 04 21:50:57 2015 -0700
@@ -28,11 +28,15 @@
 ## @deftypefnx {Function File} {[@var{x}, @var{resnorm}, @var{residual}, @var{exitflag}, @var{output}] =} lsqnonneg (@dots{})
 ## @deftypefnx {Function File} {[@var{x}, @var{resnorm}, @var{residual}, @var{exitflag}, @var{output}, @var{lambda}] =} lsqnonneg (@dots{})
 ## Minimize @code{norm (@var{c}*@var{x} - d)} subject to
-## @code{@var{x} >= 0}.  @var{c} and @var{d} must be real.  @var{x0} is an
-## optional initial guess for @var{x}.
-## Currently, @code{lsqnonneg}
-## recognizes these options: @qcode{"MaxIter"}, @qcode{"TolX"}.
-## For a description of these options, see @ref{XREFoptimset,,optimset}.
+## @code{@var{x} >= 0}.
+##
+## @var{c} and @var{d} must be real.
+##
+## @var{x0} is an optional initial guess for @var{x}.
+##
+## Currently, @code{lsqnonneg} recognizes these options: @qcode{"MaxIter"},
+## @qcode{"TolX"}.  For a description of these options, see
+## @ref{XREFoptimset,,optimset}.
 ##
 ## Outputs:
 ##
@@ -47,10 +51,10 @@
 ##
 ## @item exitflag
 ##
-## An indicator of convergence.  0 indicates that the iteration count
-## was exceeded, and therefore convergence was not reached; >0 indicates
-## that the algorithm converged.  (The algorithm is stable and will
-## converge given enough iterations.)
+## An indicator of convergence.  0 indicates that the iteration count was
+## exceeded, and therefore convergence was not reached; >0 indicates that the
+## algorithm converged.  (The algorithm is stable and will converge given
+## enough iterations.)
 ##
 ## @item output
 ##