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

Optional properties for hovercafts with default values:

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