Words built are added to a list.

The words built are added to a list, which is shown in the right hand
window. After the completed words, the current word is displayed as
it's being built.
Added WORD_LIST_POS to constants.

Made the CYAN colour darker so it doesn't clash with the word list
background when it's used for the word currrently being built.
Moved initial grid creation to a Builder class.

reset_word turns off selection for the constituent letters.
Added some sounds for completed words
Removed redundant stuff and updated WORDLIST...

WORDLIST now has a position and a size.
Redundant colours have been removed.
Added sounds and fonts.
Added #include? to return word inclusion.
Words are now scored.

Built words are displayed with a score and total now.