Improve Javadoc Formatting

[rheitjoh]

I just rendered the math Javadoc and noticed that Javadoc does not support markdown type paragraph formatting, i.e. inserting an empty line between paragraphs. This leads to a lot of block of texts without any formatting applied. Instead, HTML tags such as <p> should be utilized.

Furthermore, code blocks should be formatted using the HTML tag <pre>, or the @code annotation for inline code.

We should take a look over the Javadoc and fix any such issues before the next release.