2 new problems when using FileIOUtils::quasi_memcmp(...)

[shinespeciall]

1. we should compare through all the Tile data to find which tile has the least difference comparing to the new tile
2. we should add logic to choose which tile to delete when find 2 similar tile and the editor is going to delete one of them. we need to reserve the tile with less feature, or change less time when loop through all the 64 nybbles. Using whatever method to find the tile with less feature to avoid leading noice pixels into some Tile16s or into the graphic.