Topic/remove window prim

[HuwCampbell]

Without bubble-gum on the horizon, having a window primitive in Core doesn't make very much sense, and causes a small inefficiency, as the edges of the windows should be precomputations, and not calculated for each fact.

[HuwCampbell]

So it's clear what this is doing, here's the code output for the flatten stage:

With this query

feature injury ~> windowed between 3 weeks and 6 weeks ~> count 1

Before this change the flattened avalanche was this

conv-2 : Time =
  TIME
conv-3 : Int =
  MAX_MAP_SIZE

acc-c-conv-4 =i 0 : Int
for_facts conv-1 : Time
        , conv-0-simpflat-4 : Error
        , conv-0-simpflat-5 : Bool
        , conv-0-simpflat-6 : String
        , conv-0-simpflat-7 : String
        , conv-0-simpflat-8 : Double
        , conv-0-simpflat-9 : Time {
    simpflat-0 = Time_minusDays# conv-2 42
    simpflat-1 = ge# conv-1 simpflat-0
    simpflat-2 = Time_minusDays# conv-2 21
    simpflat-3 = ge# simpflat-2 conv-1

    if (and# simpflat-1 simpflat-3)
    {
        acc-c-conv-4 =r acc-c-conv-4
        acc-c-conv-4 =w add# acc-c-conv-4 1
    }   
}
c-conv-4 =r acc-c-conv-4
output repl:output : Int

After

conv-2 : Time =
  TIME
conv-3 : Int =
  MAX_MAP_SIZE

conv-5 = Time_minusDays# conv-2 42
conv-6 = Time_minusDays# conv-2 21
acc-c-conv-4 =i 0 : Int

for_facts conv-1 : Time
        , conv-0-simpflat-0 : Error
        , conv-0-simpflat-1 : Bool
        , conv-0-simpflat-2 : String
        , conv-0-simpflat-3 : String
        , conv-0-simpflat-4 : Double
        , conv-0-simpflat-5 : Time {
    anf-1 = ge# conv-1 conv-5
    anf-0 = ge# conv-6 conv-1

    if (and# anf-1 anf-0)
    {
        acc-c-conv-4 =r acc-c-conv-4
        acc-c-conv-4 =w add# acc-c-conv-4 1
    }
}
c-conv-4 =r acc-c-conv-4
output repl:output : Int =
  c-conv-4 : Int