Aliases for column names
When I work with Pandas DataFrames, I prefer to keep the full column names for clarity. So when I print out the `head`, or use describe, I get a meaningful table. However, this also means I have column names like "Time of Sale" that become annoying to type out. 

A nice compromise seems like it would be to have short "aliases" for column names. For instance, I can define the `tos` average for the above, perhaps like so:

```
df = pd.read_csv(...)
df.set_alias({'Time of Sale' : 'tos'})
```

Then, the `__get_attribute__` method can look up aliases in addition to column names, so I can refer to that column simply as `df.tos`. But for all other purposes, the columns name is still the descriptive full name.

Would this make sense?
