explorer: merge search and terminal

[haraldschilly]

So, this isn't perfect, there is really a lot going on, but I think this hits the general idea. All the features I'm aware of are still the same.

What I changed is

• where the "terminal mode" banner appears (further up)
• checking for the return key for submitting the mini terminal command in the keydown handler (and not a <form ...> tag wrapped around the input box
• The icons for showing other users' presence is further to the right, because in the middle it feels awkward (chat is everywhere to the right)
• The intended flex layout is 2:1, but it's not really visible in the screencast. It also wraps as before, if really narrow.

additionally: this fixes a few typos and Antd deprecations

screen-capture.2.webm

[williamstein]

wow, that looks awesome!!