Fix javadoc errors in build

[emxsys]

The build output is littered with 200 javadoc warnings and errors. For instance,

 error: self-closing element not allowed
 * <p/>

error: block element not allowed within inline element <code>: pre
 * <pre>

warning: empty <p> tag
 * <p/> <p>blah blah blah:</p>

The javadoc text should be edited to eliminate this noisy output from the build.

[wcmatthysen]

I can help with this. The javadoc parser in Java 8 produces strict HTML. It is just a matter of going through the comments and editing it to pass the requirements of the parser. We'll need to fix this in any case if we want to build with Maven or Gradle as the build will fail. This is discussed here.

[emxsys]

@wcmatthysen Thanks. But, I hope you haven't started yet. I'm in the middle of making the changes now. :)

[wcmatthysen]

Nope, I haven't started with it. It looks like a lot of small changes scattered throughout the code. Mostly self-closing paragraph fixes from what I saw in the error log.