Expand plot axes thickness to fit their labels (#3921)

Expand the plot axis thickness as the contained plot axis labels get
wider.

This fixes a problem where the plot labels would otherwise get clipped.


![plot-axis-expansion](https://github.com/emilk/egui/assets/1148717/4500a26e-4a11-401d-9e8e-2d98d02ef3b7)

crates/emath/src/rot2.rs

@@ -28,6 +28,7 @@ pub struct Rot2 {
 /// Identity rotation
 impl Default for Rot2 {
     /// Identity rotation
+    #[inline]
     fn default() -> Self {
         Self { s: 0.0, c: 1.0 }
     }
@@ -39,29 +40,35 @@ impl Rot2 {
 
     /// Angle is clockwise in radians.
     /// A 𝞃/4 = 90° rotation means rotating the X axis to the Y axis.
+    #[inline]
     pub fn from_angle(angle: f32) -> Self {
         let (s, c) = angle.sin_cos();
         Self { s, c }
     }
 
+    #[inline]
     pub fn angle(self) -> f32 {
         self.s.atan2(self.c)
     }
 
     /// The factor by which vectors will be scaled.
+    #[inline]
     pub fn length(self) -> f32 {
         self.c.hypot(self.s)
     }
 
+    #[inline]
     pub fn length_squared(self) -> f32 {
         self.c.powi(2) + self.s.powi(2)
     }
 
+    #[inline]
     pub fn is_finite(self) -> bool {
         self.c.is_finite() && self.s.is_finite()
     }
 
     #[must_use]
+    #[inline]
     pub fn inverse(self) -> Self {
         Self {
             s: -self.s,
@@ -70,6 +77,7 @@ impl Rot2 {
     }
 
     #[must_use]
+    #[inline]
     pub fn normalized(self) -> Self {
         let l = self.length();
         let ret = Self {
@@ -95,6 +103,7 @@ impl std::fmt::Debug for Rot2 {
 impl std::ops::Mul<Self> for Rot2 {
     type Output = Self;
 
+    #[inline]
     fn mul(self, r: Self) -> Self {
         /*
         |lc -ls| * |rc -rs|
@@ -111,6 +120,7 @@ impl std::ops::Mul<Self> for Rot2 {
 impl std::ops::Mul<Vec2> for Rot2 {
     type Output = Vec2;
 
+    #[inline]
     fn mul(self, v: Vec2) -> Vec2 {
         Vec2 {
             x: self.c * v.x - self.s * v.y,
@@ -123,6 +133,7 @@ impl std::ops::Mul<Vec2> for Rot2 {
 impl std::ops::Mul<Rot2> for f32 {
     type Output = Rot2;
 
+    #[inline]
     fn mul(self, r: Rot2) -> Rot2 {
         Rot2 {
             c: self * r.c,
@@ -135,6 +146,7 @@ impl std::ops::Mul<Rot2> for f32 {
 impl std::ops::Mul<f32> for Rot2 {
     type Output = Self;
 
+    #[inline]
     fn mul(self, r: f32) -> Self {
         Self {
             c: self.c * r,
@@ -147,6 +159,7 @@ impl std::ops::Mul<f32> for Rot2 {
 impl std::ops::Div<f32> for Rot2 {
     type Output = Self;
 
+    #[inline]
     fn div(self, r: f32) -> Self {
         Self {
             c: self.c / r,