Optional support for hovercrafts, cars and missiles and fix of #79,80,81

Optional properties for hovercafts with default values:

all these properties have effect only to translation, not rotation of the craft.

canHover: false # boolean if it will check hovering

hoverLimit: 0 # int 0 is perfect for cars, its used when canHover or useGravity - it make step only over one
block (don't use too big numbers! each number means one (with useGravity - two) translation check process!)

harvestBlocks: # destroyed blocks (array of strings, default empty)
#f.e:

    LONG_GRASS
    DOUBLE_PLANT #add flowers etc.

useGravity: false # boolean - try to go one block down each step of move (it checks hoverLimit count layers
under craft , independent on canHover)

canHoverOverWater: true # boolean - prevent hovering over water (it checks hoverLimit count layers under craft)

moveEtities: true # boolean - if false, it prevents kamikaze and rocket drivers and causes release craft after cruise activation

corrected minHeightLimit and maxHeightLimit to 0 and 255, maxHeightLimit can be now same as minHeightLimit

bug fixes:

#79 (partial fix - only when moveEntities: false) ... when moveEntitites: true - there is still problem with activation from outside of the craft that isn't recognize as craft-leaving-event sometimes.

#80, #81 - same bug, fixed