Added guard conditions before manipulating DOM elements.

Added guard conditions to check if the 'floatdivleft' and
'floatdivright' DOM elements exist before trying to add them to
floatingMenu.
Fixed JSHint warning messages about misplaced semicolons
Wordclouds should now display if DOM controls are missing

Added some guard conditions to check if the DOM elements
'display_plain_words' and 'required_idf_filter' exist.  If these
elements don't exist, the code should assume sane defaults that still
allow the wordclouds to be displayed.
paint_tokens() can now add classes to wordcloud token <span>'s
Fixed typo in CSS selector that affected font size slider
Added guard condition to draw_wordcloud() to prevent race condition

Without the guard condition, draw_wordcloud() would sometimes try to
draw the wordcloud before the wordcloud data had been loaded.
Modified get_size() so that fonts weren't stuck at maximum size

Merged in a change that Glen made to the VaporEngine version of
dynamic_wordclouds.js that prevents the font size for all wordcloud
tokens to be set to the maximum size.
Removed commented out code that duplicated uncommented code
Fixed JSHint warning messages about using dot notation instead of brackets
Fixed JSHint warnings about "Expected an assignment or function call and instead saw an expression".
Removed assignment to unused variable min_observations_required
Removed unused global variable last_computed_settings
Simplified way options are passed to make_me_a_venncloud()
Removed unused click handlers defaulLeftClickHandler() and defaultRightClickHandler

These functions were not being used, and default click handlers are
already being assigned to the settings object 's'.
Merged in update_displayed_token() and junk_displayed_token() from VaporEngine fork
Added proposed API document.
Fixed typo
Added info about sorting functions
Merge pull request #1 from charman/master

Bugfixes