Add a button to delete word
Hide the delete word button when click in the background
Delete a word from the list
Avoid show the delete button if the animation is running

The animation is broken if delete while other words are falling.
Show the error message changing the alpha slowly
Make the wordlist animation faster
When delete a word in the list, remove the element from the internal array
Remove the grid from the word matrix
Use grey color in the word selection
Add shadow to the word list according to the design proposed
Show the Start button disabled when no words in the list
Fix calcule canvas height on non xo
Make sure every variable is initialized as 'var'
Add ';' after every '}'