mapgen.lua: Add dirt/sand/gravel blob ores for mgv5/mgv7
mapgen.lua: Add dirt/sand/gravel blob ores for mgv5/mgv7

Create register ores function. Select and order functions per mapgen
Use blob ore for clay. Update ore height_min/max to y_min/max
Tune flower amount

evrooije/beerarchy,evrooije/beerarchy,evrooije/beerarchy