Luby sequence controls restart and var activity decay rate

[shnarazk]

0.17 uses state model and dynamic restart controller simultaneously. But it's not in a harmonic way.
Now 0.18 uses Luby sequence to decide when solver checks restart conditions.

Furthermore, the same sequence also controls var activity decay rate directly to archive both of deep search mode and exploration mode.

And replace time-consuming Luby with an alternative (count zeros?).

# 0.16.1, timeout:2000 on localhost @ 2024-08-11T20:47:29
solver,       num,                       target,     time
"0cb630b8",          1,                 "UF250(100)",   54.296
"0cb630b8",          2,                "UUF250(100)",  188.136
med:    93.862, max:   144.630,           total:  187.723
solver,       num,                       target,     time
"splr-0.17.3",       1,                 "UF250(100)",   34.514
"splr-0.17.3",       2,                "UUF250(100)",  126.764
med:    80.639, max:   126.764,           total:  161.278