Make main code less directly dependent on termbox2

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/tui/Cell.zig

@@ -0,0 +1,23 @@
+const interop = @import("../interop.zig");
+
+const termbox = interop.termbox;
+
+const Cell = @This();
+
+ch: u32,
+fg: u32,
+bg: u32,
+
+pub fn init(ch: u32, fg: u32, bg: u32) Cell {
+    return .{
+        .ch = ch,
+        .fg = fg,
+        .bg = bg,
+    };
+}
+
+pub fn put(self: Cell, x: usize, y: usize) void {
+    if (self.ch == 0) return;
+
+    _ = termbox.tb_set_cell(@intCast(x), @intCast(y), self.ch, self.fg, self.bg);
+}