Feature template vecs [1].

my bad,...for issues #1847, #1821.

this will make templates for all vecs and give back the old float vecs, for now...it can be better, but it won't break anything. 

i'm trying to get this ofVec_ to be the base class...i'm still trying to get this working, but it's breaking the core... 

```
template <typename VecType, u int Dim>
class ofVec_ {
    VecType v[Dim];
    ofVec_();
    
    ofVec_( const ofVec_<VecType, Dim> );
    
    template <typename VecType2, u int Dim2>
    ofVec_( const ofVec_<VecType2, Dim2> );

    ofVec_ operator+=(...)
}

template <typename VecType>
class ofVec3_ : public ofVec_<VecType, 3> {
      VecType& x, y, z;
      dot(), cross();
      using ofVec_::operator+=;
}
```

Any ideas?