treesitter-context integration

[xzbdmw]

It looks like with line_shift_down=2

with line_shift_down=1

with line_shift_down=0

the config option now is

        per_buffer_config = {
            treesitter_context = {
                line_shift_down = 2, -- how many lines shift down from center, so cursor above will have actual code not influenced by context.
            },
            lines = 6,
        },

note: the zindex should be lower than context's window Please try this branch to test it, we can make this option undocumented, test it for now and wait this to merge( I tried to make it work out of box, but our window opens too fast to determine bufnr in WinEnter autocmd). https://github.com/nvim-treesitter/nvim-treesitter-context/pull/419