removed unnecessary variable assignment
color: moved RGB constants to module level
gen_values: precalculate sin() param factor
simplified and optimized offset calculation
replaced int(floor()) with int()
gen_values: siplified increment operation
test_sstv: allow for rounding differences
gen_samples: replaced int(round()) with int()
moved freq * factor outside sampling loop
removed unused import math.floor
gen_values: initialize local variable 'sample'

although in practice, this shouldn't happen -- I tried lowering the
sample rate, and even at 10 samples/sec with Martin M1, it worked, and
SSTV requires at least 4000 samples/sec

(1 sample/sec raises an error though, if you'd like to try)
bumped version to v0.1.9