Allow using heterogeneous arrays (#434)

This is valid since TOML 1.0

toml/decoder.py

diff --git a/toml/decoder.py b/toml/decoder.py
index 6f23ec1..63869ad 100644
--- a/toml/decoder.py
+++ b/toml/decoder.py
@@ -942,7 +942,6 @@
         return False
 
     def load_array(self, a):
-        atype = None
         retval = []
         a = a.strip()
         if '[' not in a[1:-1] or "" != a[1:-1].split('[')[0].strip():
@@ -1024,11 +1023,6 @@
             a[i] = a[i].strip()
             if a[i] != '':
                 nval, ntype = self.load_value(a[i])
-                if atype:
-                    if ntype != atype:
-                        raise ValueError("Not a homogeneous array")
-                else:
-                    atype = ntype
                 retval.append(nval)
         return retval