Preliminary implementation of a hashmap, unfinished

Missing features:
  * keys other than strings
  * more than 8 values in the hashmap
  * growing a map when needed
  * initial size hint
  * delete(m, key)
  * iterators (for range)
  * initializing global maps
  * ...more?

README.markdown

@@ -46,11 +46,11 @@ Currently supported features:
   * standard library (but most packages won't work due to missing language
     features)
   * slices (partially)
+  * maps (very rough, unfinished)
 
 Not yet supported:
 
   * float, complex, etc.
-  * maps
   * garbage collection
   * defer
   * closures