doc: Spellcheck documentation ahead of 4.4 release. * aspell-octave.en.pws: Add new words to Octave-only spelling dictionary. Remove exception words which are no longer used in manual. * basics.txi, bugs.txi, func.txi, geometry.txi, install.txi, matrix.txi, package.txi, plot.txi, poly.txi, preface.txi, quad.txi, sparse.txi, strings.txi, vectorize.txi, data.cc, defaults.cc, file-io.cc, pinv.cc, quadcc.cc, qz.cc, rand.cc, schur.cc, syscalls.cc, sysdep.cc, toplev.cc, amd.cc, audioread.cc, colamd.cc, dmperm.cc, symrcm.cc, quadgk.m, quadl.m, imfinfo.m, rgb2gray.m, javachk.m, usejava.m, unpack.m, fzero.m, glpk.m, pqpnonneg.m, stemleaf.m, print.m, polyfit.m, blackman.m, bicgstab.m, cgs.m, eigs.m, pcg.m, tfqmr.m, gallery.m, rosser.m, toeplitz.m, vander.m, isstrprop.m: Add @nospell{} macro around proper names and other words which aspell should not check. Correct misspellings identified by aspell.

--- a/libinterp/corefcn/quadcc.cc	Mon Mar 26 22:54:24 2018 +0200
+++ b/libinterp/corefcn/quadcc.cc	Mon Mar 26 10:45:04 2018 -0700
@@ -1561,8 +1561,8 @@
 disabled with @code{warning ("off", "Octave:quadcc:RelTol-conversion")}.
 
 Reference: @nospell{P. Gonnet}, @cite{Increasing the Reliability of Adaptive
-Quadrature Using Explicit Interpolants}, ACM Transactions on Mathematical
-Software, Vol. 37, Issue 3, Article No. 3, 2010.
+Quadrature Using Explicit Interpolants}, @nospell{ACM} Transactions on
+Mathematical Software, Vol. 37, Issue 3, Article No. 3, 2010.
 @seealso{quad, quadv, quadl, quadgk, trapz, dblquad, triplequad}
 @end deftypefn */)
 {