Jump to Date

#### Is your feature request related to a problem? Please describe.

Finding old messages can be very painful. You need to scroll far and wait for batches of messages to be fetched from the server. This also uses a lot of data as it downloads all of the messages and images between now and the date you care about.

#### Describe the solution you'd like.
There should be a feature to jump to an arbitrary date. Once there you can scroll to nearby messages as normal.

#### Describe alternatives you've considered.

In a non-encrypted room you can try to search for a message that you remember from an approximate time. But that requires remembering a message and only works in unencrypted rooms.

Faster history loading would also mitigate the issue but will always be slow on slow connections.