Fix inconsistencies in javadocs.

These changes were made with consistency in mind, in relation to the rest of the project:
 - Every new paragraph now begins with a <p> tag.
 - <p> tags no longer have whitespace immediately after them.
 - <p> tags are now on the same line as the first sentence in the paragraph they encapsulate.
 - Paragraphs are now separated by an empty new line.
 - <em> tags are no longer followed by multiple white spaces.