v2.0.9.7

- implemented 'note and letters' addon from Damjan & Trikzter and
spreaded the items among maps and loot (texts added to
st_items_quest.xml)

- slightly lowered zoom rates of mutants and separated the spawns of
antagonistic species more

- stamina depletion rate is slightly smaller for each additional kg (for
all PC classes)

- significantly lowered aim zoom rate of pistols