fix Hash default and min value
- default value must be low, because we actually allocate it before the
value of the option is set by setoption. This is bad practice and the
UCI protocol specifically says not to do that. Something to fix later.
- We sometimes want to have the lowest hash value possible. This is

Also removed some dead code while at it.
useful to simulate strong hash pressure while using very fast tc. So
make the min value 1 instead of 16.