rbind with PooledDataVec should unify pools

[juliadata]

rbind with PooledDataVec should unify pools

[tshort]

I think this works now.

julia> d = DataFrame({PooledDataVec[1,2],[3,4]})
DataFrame  (2,2)
        x1 x2
[1,]     1  3
[2,]     2  4

julia> d2 = DataFrame({PooledDataVec[11,22],[3,4]})
DataFrame  (2,2)
        x1 x2
[1,]    11  3
[2,]    22  4

julia> rbind(d,d2)
DataFrame  (4,2)
        x1 x2
[1,]     1  3
[2,]     2  4
[3,]    11  3
[4,]    22  4


julia> rbind(d,d2) | idump
DataFrame 
  columns: Array(Any,(2,))
    1: PooledDataVec{Int64} 
      refs: Array(Uint16,(4,)) [0x0001, 0x0002, 0x0003, 0x0004]
      pool: Array(Int64,(4,)) [1, 2, 11, 22]
      filter: Bool false
      replace: Bool false
      replaceVal: Int64 0
    2: Array(Int64,(4,)) [3, 4, 3, 4]
  colindex: Index 
    lookup: Dict{Union(UTF8String,ASCIIString),Int64} 
      keys: Array(Any,(16,))
        1: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        2: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        3: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        4: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        5: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        6: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        7: ASCIIString 
          data: Array(Uint8,(2,)) [0x78, 0x31]
        8: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        9: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        10: ASCIIString 
          data: Array(Uint8,(2,)) [0x78, 0x32]
      vals: Array(Any,(16,))
        1: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        2: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        3: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        4: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        5: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        6: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        7: Int64 1
        8: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        9: Symbol __c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
        10: Int64 2
      ndel: Int64 0
      deleter: identity
    names: Array(Union(UTF8String,ASCIIString),(2,)) ["x1", "x2"]