doc: Update more docstrings to have one sentence summary as first line. Reviewed io, java, linear-algebra, prefs, and set script directories. * scripts/io/beep.m, scripts/io/dlmwrite.m, scripts/io/importdata.m, scripts/io/strread.m, scripts/io/textread.m, scripts/java/javaArray.m, scripts/java/java_get.m, scripts/java/java_set.m, scripts/java/javaaddpath.m, scripts/java/javachk.m, scripts/java/javaclasspath.m, scripts/java/javamem.m, scripts/java/javarmpath.m, scripts/linear-algebra/bandwidth.m, scripts/linear-algebra/commutation_matrix.m, scripts/linear-algebra/cond.m, scripts/linear-algebra/condest.m, scripts/linear-algebra/cross.m, scripts/linear-algebra/duplication_matrix.m, scripts/linear-algebra/expm.m, scripts/linear-algebra/housh.m, scripts/linear-algebra/isdefinite.m, scripts/linear-algebra/ishermitian.m, scripts/linear-algebra/issymmetric.m, scripts/linear-algebra/istril.m, scripts/linear-algebra/istriu.m, scripts/linear-algebra/krylov.m, scripts/linear-algebra/logm.m, scripts/linear-algebra/normest.m, scripts/linear-algebra/null.m, scripts/linear-algebra/onenormest.m, scripts/linear-algebra/orth.m, scripts/linear-algebra/qzhess.m, scripts/linear-algebra/rank.m, scripts/linear-algebra/rref.m, scripts/linear-algebra/vech.m, scripts/path/matlabroot.m, scripts/prefs/addpref.m, scripts/prefs/getpref.m, scripts/prefs/ispref.m, scripts/prefs/rmpref.m, scripts/prefs/setpref.m, scripts/set/powerset.m, scripts/set/setdiff.m: Update more docstrings to have one sentence summary as first line.

--- a/scripts/linear-algebra/rref.m	Sun May 03 12:58:42 2015 -0700
+++ b/scripts/linear-algebra/rref.m	Sun May 03 15:36:23 2015 -0700
@@ -20,12 +20,14 @@
 ## @deftypefn  {Function File} {} rref (@var{A})
 ## @deftypefnx {Function File} {} rref (@var{A}, @var{tol})
 ## @deftypefnx {Function File} {[@var{r}, @var{k}] =} rref (@dots{})
-## Return the reduced row echelon form of @var{A}.  @var{tol} defaults
-## to @code{eps * max (size (@var{A})) * norm (@var{A}, inf)}.
+## Return the reduced row echelon form of @var{A}.
 ##
-## Called with two return arguments, @var{k} returns the vector of
-## "bound variables", which are those columns on which elimination
-## has been performed.
+## @var{tol} defaults to
+## @code{eps * max (size (@var{A})) * norm (@var{A}, inf)}.
+##
+## The optional return argument @var{k} contains the vector of
+## "bound variables", which are those columns on which elimination has been
+## performed.
 ##
 ## @end deftypefn