vectorized operations with pd.Series of pd.Interval data 
Is there a plan to allow vectorized operations on pd.Series of pd.Interval data in the future -- perhaps just for the syntactic sugar?


*  constructing the pd.Series of interval values
```python
df['range'] = pd.Interval(df['start'], df['end'])
# instead of 
df['range'] = df.apply(lambda r: pd.Interval(r['start'], r['end']), axis=1)
```

* working with pd.Series of interval values 
```python
10 in df['range'] 
# instead of
df['range'].apply(lambda x: 10 in x)
```

```python
df['range'].length
# instead of
df['range'].apply(lambda x: x.length)
```

```python
df['range'] + 10
# instead of
df['range'].apply(lambda x: x + 10)
```

I could imagine an interface similar to the `pd.Series.str`. For example, operations might look like:

```python
df['range'].intv.contains(10)
df['range'].intv.length
df['range'].intv + 10
```

