automatically prevent filling needs when consumer is temporary filled
added method to fetch all build tiles of an unit

used to get all the build tiles underneath a structure (or unit)
tiles manager to automatically makes tiles under structures unbuildable
added mode accessors to allow changing tiles grid display  mode
added buttons to switch tiles grid display mode quickly
(debug) do not save tiles on exit until code debug finished
fixed incorrect allocation of units (walk) tiles and reduced coloring cpu use