fixed_wide: add midpoint

lib/fixed_wide/src/fixed.rs

@@ -64,6 +64,10 @@ impl<const N:usize,const F:usize> Fixed<N,F>{
 	pub const fn abs(self)->Self{
 		Self::from_bits(self.bits.abs())
 	}
+	#[inline]
+	pub const fn midpoint(self,other:Self)->Self{
+		Self::from_bits(self.bits.midpoint(other.bits))
+	}
 }
 impl<const F:usize> Fixed<1,F>{
 	/// My old code called this function everywhere so let's provide it