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/signal/filter2.m	Mon May 04 14:22:02 2015 -0700
+++ b/scripts/signal/filter2.m	Mon May 04 21:50:57 2015 -0700
@@ -19,9 +19,10 @@
 ## -*- texinfo -*-
 ## @deftypefn  {Function File} {@var{y} =} filter2 (@var{b}, @var{x})
 ## @deftypefnx {Function File} {@var{y} =} filter2 (@var{b}, @var{x}, @var{shape})
-## Apply the 2-D FIR filter @var{b} to @var{x}.  If the argument
-## @var{shape} is specified, return an array of the desired shape.
-## Possible values are:
+## Apply the 2-D FIR filter @var{b} to @var{x}.
+##
+## If the argument @var{shape} is specified, return an array of the desired
+## shape.  Possible values are:
 ##
 ## @table @asis
 ## @item @qcode{"full"}
@@ -34,8 +35,8 @@
 ## trim @var{x} after filtering so edge effects are no included.
 ## @end table
 ##
-## Note this is just a variation on convolution, with the parameters
-## reversed and @var{b} rotated 180 degrees.
+## Note this is just a variation on convolution, with the parameters reversed
+## and @var{b} rotated 180 degrees.
 ## @seealso{conv2}
 ## @end deftypefn