Custom Set Type

Since golang doesn't support a primitive Set DataStrucutre, set is
implemented as Custom Data Type.

API
===

```go
   // Initialize a new Set
   newStr := NewSetOfStr()
   //Add an element into the set
   newStr.add("foobar")
   //Remove an element from the set
   newStr.del("foobar")
   //Check membership
   newStr.isMember("foobar")
   //Set Cardinality
   newStr.Size()
   //Set Union
   newStr.Union(newStrB)
   //Set Intersection
   newStr.Intersect(newStrB)
```

Also an array can be converted into a Set using `CastToSet` convenience
method.
IsPompous final cut

The `pomposity` score is actually a Jacard Index between the corpus and
the incoming tweet.

Jacard Index of two sets `A` and `B` is defined as

```math
    Jacard = |A n B| div |A u B|
```