DEPR: Indexers will warn FutureWarning when used with a scalar indexer this is floating-point (GH4892)
closes #4892

numpy is doing this i 1.9 IIRC, and Scipy already did it. in 0.13.3

 Indexers will warn `FutureWarning` when used with a scalar indexer and a non-floating point Index

```
# non-floating point indexes can only be indexed by integers / labels
In [1]: Series(1,np.arange(5))[3.0]
        pandas/core/index.py:469: FutureWarning: scalar indexers should not be floating point unless a    floating index
Out[1]: 1

In [5]: Series(1,np.arange(5)).iloc[3.0]
        pandas/core/index.py:463: FutureWarning: scalar indexers should not be floating point unless a floating index
Out[5]: 1

# these are Float64Indexes, so integer or floating point is acceptable
In [3]: Series(1,np.arange(5.))[3]
Out[3]: 1

In [4]: Series(1,np.arange(5.))[3.0]
Out[4]: 1
```

I know what you mean, but this error message is a little impenetrable.
Maybe we should say: FutureWarning: scalar indexers for {klass} should be
int and not float.

And fill in klass with the index type.
 ok...sure!

I think that ALL warnings should purposely be as confusing as possible!
 Haha
 ```
In [2]: Series(1,np.arange(5)).iloc[3.0]
pandas/core/index.py:463: FutureWarning: scalar indexers for index type Int64Index should be integers and not floating point
```
