Merge pull request #1142 from tionis/thaw

added thaw to complement freeze

src/boot/boot.janet

@@ -2142,6 +2142,19 @@
     :buffer (string x)
     x))
 
+(defn thaw
+  `Thaw an object (make it mutable) and do a deep copy, making
+  child value also mutable. Closures, fibers, and abstract
+  types will not be recursively thawed, but all other types will`
+  [ds]
+  (case (type ds)
+    :array (walk-ind thaw ds)
+    :tuple (walk-ind thaw ds)
+    :table (walk-dict thaw (table/proto-flatten ds))
+    :struct (walk-dict thaw (struct/proto-flatten ds))
+    :string (buffer ds)
+    ds))
+
 (defn macex
   ``Expand macros completely.
   `on-binding` is an optional callback for whenever a normal symbolic binding