seasonal harvesting from trees and shrubs

now we can harvest the fruit trees and blueberries, strawberries year after year.
also unified the harvest blueberries, strawberries and trees iexamine function.


tested and seems to work. comments welcome.
Did you use the string "HARVESTED" (without "TFLAG_") in init_ter_bitflag_map/ter_bitflags and the enum value TFLAG_HARVESTED?