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/durbinlevinson.m	Mon May 04 14:22:02 2015 -0700
+++ b/scripts/signal/durbinlevinson.m	Mon May 04 21:50:57 2015 -0700
@@ -20,13 +20,13 @@
 ## @deftypefn {Function File} {} durbinlevinson (@var{c}, @var{oldphi}, @var{oldv})
 ## Perform one step of the @nospell{Durbin-Levinson} algorithm.
 ##
-## The vector @var{c} specifies the autocovariances @code{[gamma_0, @dots{},
-## gamma_t]} from lag 0 to @var{t}, @var{oldphi} specifies the
-## coefficients based on @var{c}(@var{t}-1) and @var{oldv} specifies the
-## corresponding error.
+## The vector @var{c} specifies the autocovariances
+## @code{[gamma_0, @dots{}, gamma_t]} from lag 0 to @var{t}, @var{oldphi}
+## specifies the coefficients based on @var{c}(@var{t}-1) and @var{oldv}
+## specifies the corresponding error.
 ##
-## If @var{oldphi} and @var{oldv} are omitted, all steps from 1 to
-## @var{t} of the algorithm are performed.
+## If @var{oldphi} and @var{oldv} are omitted, all steps from 1 to @var{t} of
+## the algorithm are performed.
 ## @end deftypefn
 
 ## Author: FL <Friedrich.Leisch@ci.tuwien.ac.at>