Minor polishment of c1b8a036bd264dad9ffd466ee9efc599a8798836

Javadoc related change.
Frame split

Frame split divides a frame into a parts
based on given ratios.
Link to frame split on Inspec page.
Default value for split ratio.
More split frame polishment:

 - adopts Tomas's approach to extract data from chunk
 - implements HTML for the page
 - minor bug fixes
Tiny frame splitter test.
Aaa Oracle compiler sucks - it cannot solve simple ambiguous references
which are simply solved by Eclipse compiler.

The code
public static float []   ar(float  ...a)   { return a; }
public static double[]   ar(double ...a)   { return a; }

is ambiguous for Oracle compiler 6.0 complaining by the following
message:

src/test/java/water/api/ConfusionMatrixTest.java:259: reference to ar is
ambiguous, both method ar(float...) in water.TestUtil and method
ar(double...) in water.TestUtil match

So I had to change signature
to arf(float...), and ard(double ...)