#7 linear inertia

Linearly decreasing inertia stops at value different
(by exactly one step) from the desired final value, e.
g. inertia 0.95 -> 0.4 in 0.7 of 1000 iterations stops
decreasing at:
700th iteration with value 0.400786. Solution (pso.m):

1)
if (iter<=w_varyfor+1) & (iter > 1)
or 2)
inertdec = (w_start-w_end)/(w_varyfor-1);