#129 submit() method does not find button tags

[Ivo Maixner]

Using version 3.0.
I have a form with <button type="submit">Label</button>.
The submit() method throws exception "No submit button found in current form."

I expect the bug is on line 1516 in net.sourceforge.jwebunit.htmlunit.HtmlUnitTestingEngineImpl:
Object[] inpt = getForm().getHtmlElementsByTagName("input").toArray();
It only looks up <input> elements.

On line 1527, however, it tries to check if it is <button> element, but I can never be, since it was not looked up in the first place.