[.25] Change equivalent value to Estimated Value

[knifewine]

On the account page, there's a column for "Equivalent Value".

When the asset value is already displayed in that denomination, the Equivalent Value column should probably just show the same value, or be blank. E.g. when the account has 0.57 USD, it's odd to display the Equivalent Value as "1 USD".

To repro:
Set account to display in USD.
Make sure account holds a non-integer amount of USD (e.g. 0.57)
Look at the Accounts screen.

[wmbutler]

I'm guessing we are doing some rounding here to provide a simpler overview. The label could definitely be better. Maybe change the label to approximate value.

[wmbutler]

See #378 Tables Rewrite as well regarding this label display.

[landry314]

But the word "equivalent" is good when it is converting from another unit but not exactly a good word when it is the same unit.

Maybe "Estimated Value"? That kind of includes both ideas.