When the memory space is asked for nearby ranges,
it should return a range.

Let a plugin tell us about where to plop a dollop.
This change includes a

1. utils namespace with a function to calculate
the worst case instruction size.
2. Dollop_t type that can be used to describe
and pass around a dollop.

that start/end on the same byte are actually
1-byte big. Update tests to confirm this.

Updates for x86-64, adjusted memory_space.cpp to have O(ln(n)) complexity instead of O(N) in a few commo cases.