Bug fixed 216

[JordanMartinez]

I think the final commit (4d86628) could be done better. However, I'm not sure how to get around a plumbing issue.
If a new EmptyParagraph is created anywhere outside of EditableStyledDocument, it doesn't have the correct style object for its emptyTextStyle (e.g. StyledDocumentBase, NormalParagraph, ReadOnlyStyledDocument). Additionally, its paragraphStyle isn't always correct either when it is created in some method in StyledDocument and ReadOnlyStyledDocument.

I think the only good solution is to remove EmptyParagraph's emptyTextStyle field and use the StyledDocument classes to check the Paragraph type before returning a style object, such as:

class StyledDocumentBase {

    StyledDocumentBase(L paragraphs, S initialStyle, PS initialParagraphStyle) {
        // normal creation code
        this.initialStyle = initialStyle;
        this.initialParagraphStyle = initialParagraphStyle;
    }

    Paragraph someOtherMethodThatCreatesANewEmptyParagraph() {
        return new EmptyParagraph(initialParagraphStyle);
    }

    S getStyleOfChar/getStyleAtPosition(int position) {
        Paragraph<S, PS> par = paragraphs.get(position);
        return par instanceof EmptyParagraph
            ? initialStyle
            : par.getStyleOfChar/getStyleAtPosition(position);
    }
}

Doing the above would require another change. ClipboardActions has a default method that creates a ReadOnlyStyledDocument, but it doesn't have any reference within itself for getting the two styles for its new constructor. So, it'd also need to have two getters for the styles. Since it's name is ClipboardActions, I wasn't sure if something should further extend that. Possibly an interface called StyledClipboardActions ?

[JordanMartinez]

Once fully implemented, I think some tests should be written for the Paragraph methods that return a Paragraph to insure that EmptyParagraph is returned instead of a NormalParagraph whose length is 0 because I'm pretty sure that part isn't error-free yet in this branch.

[JordanMartinez]

Closing as EmptyParagraph/NonEmptyParagraph approach to solving bug is "orthogonal" (#216).