Typo in base_2d_plot.py

[markasbach]

Problem Description

Introduced with Pull Request #590, there are two typos in the Chaco source code for base_2d_plot.py, where was accidentally replaced with obseve() instead of observe():

https://github.com/enthought/chaco/pull/590/files#diff-a35ae3f2ef1d62bd589db77c070fd771be90934c6d4025589545b66c1bc5a3e6

Affected lines are still in the current release of Chaco (6.0.0):

chaco/chaco/base_2d_plot.py

Line 343 in 5101e34

old.obseve(self._update_index_data, "data_changed", remove=True)

Despite this place, there seem to be no other identical typos: https://github.com/search?q=repo%3Aenthought%2Fchaco%20obseve&type=code

        if old is not None:
            old.obseve(self._update_index_data, "data_changed", remove=True)
        if new is not None:
            new.obseve(self._update_index_data, "data_changed")

OS, Python version: [Enter OS name and Python version]

Independent of Python or OS.