REF: use inherit_names for TimedeltaIndex

[jbrockmendel]

ATM we have two separate ways of doing inheritance/pass-through for our EA-backed Indexes. This moves TDI over to all-inherit_names, Will do the same for other EA-Indexes in their own PRs.

[jorisvandenbossche]

Can you explain a bit what's the difference between the two mechanisms? (the delegate_names vs inherit_names)

[jbrockmendel]

Can you explain a bit what's the difference between the two mechanisms? (the delegate_names vs inherit_names)

1. inherit_names has a kwarg that allows us to inherit a property as a cache_readonly
2. inherit_names works for class attributes, i.e. not properties or methods
3. inherit_names lets us to avoid repeating boilerplate of PandasDelegate

[jreback]

thanks @jbrockmendel

[jorisvandenbossche]

inherit_names works for class attributes, i.e. not properties or methods

What do you mean exactly? In this PR it's being used for methods? (eg sum, median, etc)

[jbrockmendel]

What do you mean exactly? In this PR it's being used for methods? (eg sum, median, etc)

e.g. We use inherit names on DatetimeIndex to inherit _bool_ops, which is just a list