Allow users to manually edit individual future years earnings

[Gregable]

Currently, the only option for future years is a slider with a single dollar value input and a number of years input. For users interested in digging in with even more detail, it would be super useful to support allowing them to manually tweak earnings in these future years.

It may also be nice to provide an option to allow folks to set a starting dollar amount and an expected annual increase (over inflation), so the series is computed automatically.