op_pool: use max cover algorithm, refactor

eth2/utils/boolean-bitfield/src/lib.rs

@@ -13,7 +13,7 @@ use std::default;
 
 /// A BooleanBitfield represents a set of booleans compactly stored as a vector of bits.
 /// The BooleanBitfield is given a fixed size during construction. Reads outside of the current size return an out-of-bounds error. Writes outside of the current size expand the size of the set.
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Hash)]
 pub struct BooleanBitfield(BitVec);
 
 /// Error represents some reason a request against a bitfield was not satisfied
@@ -170,6 +170,7 @@ impl cmp::PartialEq for BooleanBitfield {
         ssz::ssz_encode(self) == ssz::ssz_encode(other)
     }
 }
+impl Eq for BooleanBitfield {}
 
 /// Create a new bitfield that is a union of two other bitfields.
 ///