Add responsive menubar to complement current togglable sidebar.

[karpov-sv]

Idea is to have most important pages directly accessible without additional clicking.

Points for discussion:

• Burger menu moved to the right to somehow fill that emtpy spot (sidebar still opens on the left). Probably when authentication will be implemented the avatar / user menu would go there, and the burger will return to leftmost slot.
• Do we need Fink logo in the leftmost spot? Would probably visually conflict with current 'search' entry.
• Small shadow is added for the whole header to slightly better separate it from the page content. Probably will need some adjustment when backgrounds are changed.

[JulienPeloton]

Thanks @karpov-sv ! Could we keep the burger on the leftmost spot? Currently, one has to click on it on the right, and move across the screen to the left to choose an option.

[karpov-sv]

The menu has to be visually balanced from both ends, so I'd not like to move everything to the left. What about this?

[karpov-sv]

Another possible solution would be splitting "actions" and "info" entries like that

[JulienPeloton]

I prefer the last option with the split :-)

[karpov-sv]

I prefer the last option with the split :-)

Ok, committed!

[JulienPeloton]

The code looks good to me -- merging?

[karpov-sv]

The code looks good to me -- merging?

I have no objections and nothing to add here, so let's do it!