changed download/upload queue counter to rounded numbers

changed default probability for undefined tiles to wall = 1, others = 0

fixed bug where probabilities of each box for undefined tiles would be shifted towards some boxes

added numbers to indicate how many downloads/uploads are left

fixed bug where undefined tiles would cause error (requires re-generating all maps, sorry), added wait time of 1s for each downloaded/uploaded map to avoid broken map previews

fixed map previews upload/download

added uploading/downloading of map previews

fixed mirror axis mirroring wrong axis

added mirror axis block placing

added script that automatically renames .txt map files to .lua