Fix a couple of problems with insert mode: flush dirty cells before we modify the screen, not after; and use grid_view_insert_cells to make space not grid_move_cells.
Fix a couple of problems with insert mode: flush dirty cells before we
modify the screen, not after; and use grid_view_insert_cells to make
space not grid_move_cells.

klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux