Move options functions to top level

[genedan]

Discovering more work to do...options functions like get_option and set_option are top-level in pandas:

In [5]: pd.get_option("display.chop_threshold")

In [6]: pd.set_option("display.chop_threshold", 2)

In [7]: pd.get_option("display.chop_threshold")
Out[7]: 2

In [8]: pd.set_option("chop", 4)

In [9]: pd.get_option("display.chop_threshold")
Out[9]: 4

They aren't in chainladder:

cl.options.get_option(...)

Let's see if we can improve the consistency of the API.