refactor: add ascii optimization to Plane.egc_length

This gives a huge performance boost to pos_to_width which is used by
find results and many other things.

src/renderer/vaxis/Plane.zig

@@ -437,26 +437,24 @@ inline fn set_font_style(style: *vaxis.Cell.Style, fs: FontStyle) void {
     }
 }
 
-inline fn is_control_code(c: u8) bool {
-    return switch (c) {
-        0...8, 10...31 => true,
-        else => false,
-    };
-}
-
 pub fn egc_length(self: *const Plane, egcs: []const u8, colcount: *usize, abs_col: usize, tab_width: usize) usize {
     if (egcs.len == 0) {
         colcount.* = 0;
         return 0;
     }
-    if (is_control_code(egcs[0])) {
+    switch (egcs[0]) {
+        0...8,
+        10...31, //control codes
+        32...126,
+        => { //ascii
             colcount.* = 1;
             return 1;
-    }
-    if (egcs[0] == '\t') {
+        },
+        '\t' => {
             colcount.* = tab_width - (abs_col % tab_width);
             return 1;
-    }
+        },
+        else => {
             var iter = vaxis.unicode.graphemeIterator(egcs);
             const grapheme = iter.next() orelse {
                 colcount.* = 1;
@@ -466,6 +464,8 @@ pub fn egc_length(self: *const Plane, egcs: []const u8, colcount: *usize, abs_co
             const w = self.window.gwidth(s);
             colcount.* = w;
             return s.len;
+        },
+    }
 }
 
 pub fn egc_chunk_width(self: *const Plane, chunk_: []const u8, abs_col_: usize, tab_width: usize) usize {