Display blockheight as Date/time

[sendbitcoin]

when youre looking at closed channels the closeheight is expressed in blockheight like this "564,957" which isn't very human readable. I have to go use an explorer if i want to know when the close happened.

it would be nice to show a date/time everywhere where blockheight is used in RTL like this:

"2019-02-27 23:55 (564,957)"

or this

"564,957 (2019-02-27 23:55)"

or with mousover display of either date/time or blockheight