<NME> value_declaration.elm
<BEF> ADDFILE
<MSG> Add code folding (#70)

This PR adds code folding to all regions that I thought made sense. It follows the global settings for default collapse, so depending on your settings, module declarations, imports, and doc comments might be collapsed when you open a file.
<DFF> @@ -0,0 +1,8 @@
+foo<fold text=' = ...'> =
+    ()</fold>
+
+(x, y)<fold text=' = ...'> =
+    (x, y)</fold>
+
+(||) a b<fold text=' = ...'> =
+    a ++ b</fold>

Add code folding (#70)