doc: Periodic grammarcheck and spellcheck of documentation. * func.txi: Correct two misspellings * cumtrapz.m, dblquad.m, quadgk.m, quadl.m, quadv.m, trapz.m, triplequad.m, cond.m, gmres.m, bzip2.m, compare_versions.m, getappdata.m, unpack.m, ver.m, glpk.m, pkg.m, axis.m, uigetdir.m, uigetfile.m, view.m, prctile.m, quantile.m, unidcdf.m, unidinv.m, isstrprop.m, balance.cc, besselj.cc, cellfun.cc, colamd.cc, dot.cc, eigs.cc, fftw.cc, matrix_type.cc, pinv.cc, qr.cc, quad.cc, quadcc.cc, qz.cc, regexp.cc, schur.cc, time.cc (gmtime), typecast.cc urlwrite.cc bitfcns.cc (bitshift), data.cc (rem, norm, merge) debug.cc (dbstatus), dirfns.cc (glob), file-io.cc (freport), load-path.cc (genpath), load-save.cc (save), mappers.cc (islower, isupper, tolower, toupper) oct-hist.cc (edit_history), ov-fcn-inline.cc (vectorize), ov.cc (subsref), syscalls.cc (stat), variables.cc (whos, clear): Improve docstrings. Removed trailing whitespace characters on line.

--- a/scripts/strings/isstrprop.m
+++ b/scripts/strings/isstrprop.m
@@ -43,10 +43,10 @@
 ## True for characters that are alphabetic or digits.
 ##
 ## @item "lower"
-## True for lower-case letters.
+## True for lowercase letters.
 ##
 ## @item "upper"
-## True for upper-case letters.
+## True for uppercase letters.
 ##
 ## @item "digit"
 ## True for decimal digits (0-9).