*bugfix: cat-in-boat to goat should okay
*when forcing an goal object because we have none, make the chance higher based on how many things we're dropping.
*add more win images
* make win images sequential rather than random.
*Make 'allowedthings' default to previous level's one.
*fix lev6 help
*bugfix: whitecats aren't ever appearing randomly?
*new object: bricks
*Don't allow extending path off the top of the grid.
*fix incorrect pluralisation "foods" in goal text
*match 3 llamas to explode them
*adjust stars required to unlock levels
*from lev5 onwards, shopping bags on right.
*powerups
*sneeze (wake up all)
*shears - clears all llamas
*magic carpet - drag to give cats a fez. Worth heaps of points.
*help for bags/prizes
*tweak required scores
*change font
*wipes between game states
*make levels specify gridw instead of gridsize
*make levels default to gridsize of previous one
*bug - things not x snapped to grid sometimes?!
*animated bg on title screen
*help text for all existing levels
*Store level progress and hiscores using localstorage
*new thing type: goats
*goat help text.
*level select screen needs "back to title"
*mechanism to force at least one of a given thing type on a level.
*better level complete animation - zoom in random cat picture.
*only redraw screen if dirty!
*switch to "star" system for unlocking levels
*fix bug when calculating whether there are any valid moves left
*fix bug in random thing selection
*animate chomps
*offset entire grid downwards to allow space for a header
*add images
*award points for stuff
*show score up the top
*animated points gaining (text fading out)
*touch events:
* touchstart: a finger is placed on a DOM element.
* touchmove: a finger is dragged along a DOM element.
* touchend: a finger is removed from a DOM element.