Add #[inline] annotation to the max function. (#34)

This function is called from `EcoVec::align` and `EcoVec::offset`
functions. Although they are marked `#[inline]`, and `max` is private,
that is not sufficient to ensure that it is inlined, and as a result,
`EcoVec::new()` and related functions have calls to `max` in them.

src/vec.rs

@@ -1176,6 +1176,7 @@ fn out_of_bounds(index: usize, len: usize) -> ! {
 }
 
 // Copy of `std::cmp::max::<usize>()` that is callable in `const` contexts
+#[inline]
 const fn max(x: usize, y: usize) -> usize {
     if x > y {
         x