ArrayTiler spacing (#44)

* add support for spacing

* fix compiler errors

Author: rohanku

substrate/src/layout/placement/array.rs

@@ -42,12 +42,24 @@ impl<'a> ArrayTilerBuilder<'a> {
         self
     }
 
+    #[inline]
+    pub fn space(&mut self, space: i64) -> &mut Self {
+        self.space = space;
+        self
+    }
+
     #[inline]
     pub fn alt_mode(&mut self, mode: impl Into<AlignMode>) -> &mut Self {
         self.alt_mode = Some(mode.into());
         self
     }
 
+    #[inline]
+    pub fn alt_space(&mut self, alt_space: i64) -> &mut Self {
+        self.alt_space = alt_space;
+        self
+    }
+
     #[inline]
     pub fn push<'b>(&mut self, tile: impl Into<Tile<'b>>) -> &mut Self
     where