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/miscellaneous/genvarname.m	Sun May 03 21:52:42 2015 -0700
+++ b/scripts/miscellaneous/genvarname.m	Mon May 04 14:22:02 2015 -0700
@@ -21,8 +21,8 @@
 ## @deftypefnx {Function File} {@var{varname} =} genvarname (@var{str}, @var{exclusions})
 ## Create valid unique variable name(s) from @var{str}.
 ##
-## If @var{str} is a cellstr, then a unique variable is created for each
-## cell in @var{str}.
+## If @var{str} is a cellstr, then a unique variable is created for each cell
+## in @var{str}.
 ##
 ## @example
 ## @group
@@ -36,8 +36,8 @@
 ## @end example
 ##
 ## If @var{exclusions} is given, then the variable(s) will be unique to each
-## other and to @var{exclusions} (@var{exclusions} may be either a string or
-## a cellstr).
+## other and to @var{exclusions} (@var{exclusions} may be either a string or a
+## cellstr).
 ##
 ## @example
 ## @group
@@ -48,8 +48,8 @@
 ## @end example
 ##
 ## Note that the result is a char array or cell array of strings, not the
-## variables themselves.  To define a variable, @code{eval()} can be
-## used.  The following trivial example sets @code{x} to @code{42}.
+## variables themselves.  To define a variable, @code{eval()} can be used. 
+## The following trivial example sets @code{x} to @code{42}.
 ##
 ## @example
 ## @group
@@ -78,8 +78,8 @@
 ##
 ## Since variable names may only contain letters, digits, and underscores,
 ## @code{genvarname} will replace any sequence of disallowed characters with
-## an underscore.  Also, variables may not begin with a digit; in this
-## case an @samp{x} is added before the variable name.
+## an underscore.  Also, variables may not begin with a digit; in this case
+## an @samp{x} is added before the variable name.
 ##
 ## Variable names beginning and ending with two underscores @qcode{"__"} are
 ## valid, but they are used internally by Octave and should generally be