Changes for large boards — Word Attack Steam update #259000

This incorporates some changes made to the Wordsearch attack game. Added option to draw the backs of cells on the board. It is sometimes possible for the camera to be 'inside' the board, effectively looking out. Therefore you might see nothing, however with this option on you'll see the reverse of the cells. This should affect the Wordsearch, Word Hunt and BattleBoard game modes. Note that this will probably reduce graphical performance. In wordsearch game, improved the performance of trying to place large numbers of words onto large boards. Previously it would top out at about 1000 words in 30seconds (depending on system performance), now it should manage 5 times as many words in that time. Note that large boards realistically don't play very well both technically and enjoyably - it would probably take days to find 1000s of words on a board.