doc: Update more docstrings to have one sentence summary as first line. Reviewed miscellaneous, sparse, strings in scripts directory. * scripts/miscellaneous/bzip2.m, scripts/miscellaneous/citation.m, scripts/miscellaneous/compare_versions.m, scripts/miscellaneous/computer.m, scripts/miscellaneous/debug.m, scripts/miscellaneous/dir.m, scripts/miscellaneous/edit.m, scripts/miscellaneous/error_ids.m, scripts/miscellaneous/fileattrib.m, scripts/miscellaneous/fullfile.m, scripts/miscellaneous/genvarname.m, scripts/miscellaneous/gzip.m, scripts/miscellaneous/mkoctfile.m, scripts/miscellaneous/news.m, scripts/miscellaneous/open.m, scripts/miscellaneous/parseparams.m, scripts/miscellaneous/recycle.m, scripts/miscellaneous/run.m, scripts/miscellaneous/swapbytes.m, scripts/miscellaneous/tar.m, scripts/miscellaneous/tmpnam.m, scripts/miscellaneous/unpack.m, scripts/miscellaneous/what.m, scripts/sparse/bicg.m, scripts/sparse/bicgstab.m, scripts/sparse/cgs.m, scripts/sparse/colperm.m, scripts/sparse/eigs.m, scripts/sparse/etreeplot.m, scripts/sparse/gmres.m, scripts/sparse/gplot.m, scripts/sparse/ichol.m, scripts/sparse/ilu.m, scripts/sparse/pcg.m, scripts/sparse/pcr.m, scripts/sparse/qmr.m, scripts/sparse/spaugment.m, scripts/sparse/spconvert.m, scripts/sparse/spdiags.m, scripts/sparse/spfun.m, scripts/sparse/spones.m, scripts/sparse/sprandsym.m, scripts/sparse/spstats.m, scripts/sparse/spy.m, scripts/sparse/svds.m, scripts/sparse/treelayout.m, scripts/sparse/treeplot.m, scripts/strings/base2dec.m, scripts/strings/bin2dec.m, scripts/strings/blanks.m, scripts/strings/cstrcat.m, scripts/strings/deblank.m, scripts/strings/dec2base.m, scripts/strings/dec2bin.m, scripts/strings/dec2hex.m, scripts/strings/findstr.m, scripts/strings/hex2dec.m, scripts/strings/index.m, scripts/strings/isletter.m, scripts/strings/isstrprop.m, scripts/strings/mat2str.m, scripts/strings/ostrsplit.m, scripts/strings/regexptranslate.m, scripts/strings/rindex.m, scripts/strings/str2num.m, scripts/strings/strcat.m, scripts/strings/strchr.m, scripts/strings/strjoin.m, scripts/strings/strjust.m, scripts/strings/strmatch.m, scripts/strings/strsplit.m, scripts/strings/strtok.m, scripts/strings/strtrim.m, scripts/strings/strtrunc.m, scripts/strings/substr.m, scripts/strings/untabify.m, scripts/time/datenum.m: Update more docstrings to have one sentence summary as first line.

--- a/scripts/time/datenum.m	Sun May 03 21:52:42 2015 -0700
+++ b/scripts/time/datenum.m	Mon May 04 14:22:02 2015 -0700
@@ -75,9 +75,14 @@
 ## Days can be fractional.
 ## @end itemize
 ##
-## @strong{Caution:} this function does not attempt to handle Julian calendars so dates before October 15, 1582 are wrong by as much as eleven days.  Also, be aware that only Roman Catholic countries adopted the calendar in 1582.  It took until 1924 for it to be adopted everywhere.  See the Wikipedia entry on the Gregorian calendar for more details.
+## @strong{Caution:} this function does not attempt to handle Julian calendars
+## so dates before October 15, 1582 are wrong by as much as eleven days.  Also,
+## be aware that only Roman Catholic countries adopted the calendar in 1582.
+## It took until 1924 for it to be adopted everywhere.  See the Wikipedia entry
+## on the Gregorian calendar for more details.
 ##
-## @strong{Warning:} leap seconds are ignored.  A table of leap seconds is available on the Wikipedia entry for leap seconds.
+## @strong{Warning:} leap seconds are ignored.  A table of leap seconds is
+## available on the Wikipedia entry for leap seconds.
 ## @seealso{datestr, datevec, now, clock, date}
 ## @end deftypefn