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/java/java_get.m	Sun May 03 12:58:42 2015 -0700
+++ b/scripts/java/java_get.m	Sun May 03 15:36:23 2015 -0700
@@ -18,12 +18,13 @@
 
 ## -*- texinfo -*-
 ## @deftypefn {Function File} {@var{val} =} java_get (@var{obj}, @var{name})
-## Get the value of the field @var{name} of the Java object @var{obj}.  For
-## static fields, @var{obj} can be a string representing the fully qualified
-## name of the corresponding class.
+## Get the value of the field @var{name} of the Java object @var{obj}.
+##
+## For static fields, @var{obj} can be a string representing the fully
+## qualified name of the corresponding class.
 ##
 ## When @var{obj} is a regular Java object, structure-like indexing can be
-## used as a shortcut syntax.  For instance, the two following statements are
+## used as a shortcut syntax.  For instance, the following two statements are
 ## equivalent
 ##
 ## @example