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/fminbnd.m	Mon May 04 14:22:02 2015 -0700
+++ b/scripts/optimization/fminbnd.m	Mon May 04 21:50:57 2015 -0700
@@ -29,8 +29,9 @@
 ## @qcode{"MaxIter"}, @qcode{"MaxFunEvals"}.  For a description of these
 ## options, see @ref{XREFoptimset,,optimset}.
 ##
-## On exit, the function returns @var{x}, the approximate minimum point
-## and @var{fval}, the function value thereof.
+## On exit, the function returns @var{x}, the approximate minimum point and
+## @var{fval}, the function value thereof.
+##
 ## @var{info} is an exit flag that can have these values:
 ##
 ## @itemize
@@ -44,11 +45,11 @@
 ## The algorithm has been terminated from user output function.
 ## @end itemize
 ##
-## Notes: The search for a minimum is restricted to be in the interval
-## bound by @var{a} and @var{b}.  If you only have an initial point
-## to begin searching from you will need to use an unconstrained
-## minimization algorithm such as @code{fminunc} or @code{fminsearch}.
-## @code{fminbnd} internally uses a Golden Section search strategy.
+## Notes: The search for a minimum is restricted to be in the interval bound by
+## @var{a} and @var{b}.  If you only have an initial point to begin searching
+## from you will need to use an unconstrained minimization algorithm such as
+## @code{fminunc} or @code{fminsearch}.  @code{fminbnd} internally uses a
+## Golden Section search strategy.
 ## @seealso{fzero, fminunc, fminsearch, optimset}
 ## @end deftypefn