Graylog Search multiple small improvements

Graylog Search display is rigid and could use the following improvements:
- Issue: It does not allow frame width sizing between the left and the right panes. The left panes take up an unnecessarily wide space, not leaving enough width for the Messages pane.
- Requested Feature: Left/Right Frame width adjustment.
- Issue: In the events frame when scrolling down, the column titles (Field Names) row scrolls as well, it should remain on top so the operator does not need to guess which fields he is looking at, especially when the field content does not hint as to its label.
- Requested Feature: Stationary field names row when scrolling down events in Messages frame.
- Issue: When the width of the displayed fields exceeds the width of the messages frame, fields on the right of the frame are not visible, and there is no way to see them.
- Requested Feature: A left-right scroll slider should be displayed at the bottom of the screen if the width required by the fields exceeds the messages frame width.
- Issue: Currently only one row of fields can be displayed in the messages frame.
- Requested Feature: Ability to display two rows of fields instead of just one, and be able to select which fields display on top of each other. For example, it makes sense to be able to display source & destination IPs on top of each other, ditto for source & destination ports, source & target domains, source & target accounts, etc...

Environment:
- Graylog Version: 2.0.0-rc.1-1
- Elasticsearch Version: 2.2.0
- MongoDB Version: 3.5.3-1
- Operating System: Debian Jessie/SID
- Browser version: Chrome v53.0.2785.113 m (64-bit)