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.
a question about flags.
i tried setting a "TFLAG_HARVESTED" in: ter_bitflags (in src/mapdata.h)
and in: init_ter_bitflag_map() (src/mapdata.cpp),
but both the: has_flag("TFLAG_HARVESTED") in here,
and the: m->has_flag("TFLAG_HARVESTED", examx, examy) in iexamine seem to never evaluate to true...
am i missing something?