add cell, character, style, color primitives

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>

src/cell.zig

@@ -0,0 +1,33 @@
+pub const Cell = struct {
+    char: Character,
+    style: Style = .{},
+};
+
+pub const Character = struct {
+    grapheme: []const u8,
+    width: usize,
+};
+
+pub const Style = struct {
+    fg: Color = .default,
+    bg: Color = .default,
+    ul: Color = .default,
+    ul_style: UnderlineStyle = .off,
+    url: ?[]const u8 = null,
+    url_params: ?[]const u8 = null,
+};
+
+pub const Color = union(enum) {
+    default,
+    index: u8,
+    rgb: [3]u8,
+};
+
+pub const UnderlineStyle = enum {
+    off,
+    single,
+    double,
+    curly,
+    dotted,
+    dashed,
+};