Merged settings and participants list

[jhthorsen]

One thing that has bugged me for a long time is how it's so difficult to get to settings for a Conversation or Connection.

This PR is a Work In Progress, but I'm opening for discussion. Here is screenshot taken from this PR:

Summary:

• The settings will be collapsed by default, but accessible just by toggling the checkbox.
• The participant groups will be open by default, but can be collapsed.
• No magical cogwheel in the main menu.

Not sure about:

• Should the "Leave" button be inside settings? I'm also considering just adding a "X", since leaving a channel is a non-destructive action. (Nothing gets deleted)
• Do we need a "Save" button for settings?
• Should the top bar stretch from side to side?
• Should the topic box be inside settings or somewhere else? Can it replace the truncated topic in the header? Or should it be a supplement?

TODO:

• All of the above...
• Add number of operators, members, ...
• Add a toggle for hiding the whole sidebar Hide/fold side panels  #746
• Store the (un)collapsed state in browser's localStorage.

[poVoq]

This translates not very well to mobile use I think.

I agree that currently it is a bit counter intuitive (on desktop at least) that the channel settings button opens a settings menu on the opposite side of the screen over the channel list. But in general having an easily accessible (and touch screen ready) channel settings button seems like not such a bad idea.

I think tiny collapsible harmonicas work somewhat ok with mouse input, but are already annoying when using touchpad and keyboard mostly.

[jhthorsen]

This translates not very well to mobile use I think.

The mobile version will stay the same as today.

I think tiny collapsible harmonicas work somewhat ok with mouse input, but are already annoying when using touchpad and keyboard mostly.

The size is the same for all checkboxes, so if there's an issue with that it has to be addressed globally.

[jhthorsen]

This is part of v8.01.