Terminal buffer manager

[mklabs]

Several commands that manage terminal buffers:

• add, edit an id (name, title) for a buffer
• list active terminal buffers, in background or in visible buffers.
• delete a terminal buffer
• Change the shell and arguments used when spawning the buffer (bash, fish, zsh)
• Redraw, when the layout is messed up, the buffer should redraw the canvas.

Ex. ``VTerm bufferId` would open the buffer previously created or init a new one.

Would be easier to have the same terminal buffer in multiple tabs for instance.

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Windows note: Tested split-term and neovim :terminal with Bash on Windows and Onivim. It works really well.

I wonder if I should add a little command to enable Windows Developper mode (if a proper configuration variable is setup, by default it would do nothing) through powershell and open the Linux distributions available in the Store.