DataRange1D NumPy FutureWarning on assigning 1d array to high_setting

In `DataRange1D`, we're getting a NumPy `FutureWarning` when setting `high_setting` or `low_setting` with a shape (1,) NumPy array. That `FutureWarning` is coming from code like this:
https://github.com/enthought/chaco/blob/e0e4f7d8bc5551191ad65295fe97f55190e87a9c/chaco/data_range_1d.py#L285

which compares the current value with the `val` array. If the current value is a string (either `"auto"` or `"track"`),and `val` is a shape `(1,)` array, NumPy will convert the string to a character array and then do a comparison, resulting in this future warning.

I *think* this is mostly benign: in a future version of NumPy, `self._high_setting != val` will be returning a shape `(1,)` array of dtype bool, and for now that should still be usable in an `if` condition. But I could see that (ab)use of bool arrays changing in some future NumPy version, and it would be good to fix this.