Try to fully resolve the NumPy format string issues. (#337)

* Test 32-bit and 64-bit Windows format strings.

* Restore buildtest.

* Added util::dtype enum and converters.

* NumpyArray and NumpyForm take a util::dtype argument.

* Replaced one #ifdef _MSC_VER.

* Centralized 'dtype_name'.

* Replaced PrimitiveType::Dtype with the new util::dtype.

* Reducer.preferred_type and Reducer.return_type are no longer used.

* Removed 'format' dependence from reducers, considerably simplifying them.

* Removed 'format_' from 'tostring_part'.

* Put Windows/32-bit integer promotion rules back in.

* Removed '#ifdef' from 'tojson_part'.

* Removed '#ifdef' from 'mergeable'.

* Removed '#ifdef' from 'merge', but its behavior does not match np.concatenate.

* Merge (ak.concatenate) follows the same type-promotion rules as np.concatenate.

* Removed '#ifdef' from 'sort' and 'argsort'.

* Removed '#ifdef' from 'copy_to'.

* All compiler '#if' checks for interpreting 'format' are replaced by 'dtype' now.

* Fixed #333.

* Form.from_numpy now exists.

.ci/azure-buildtest-awkward.yml

@@ -7,6 +7,7 @@ trigger:
     exclude:
       - README.md
       - VERSION_INFO
+      - .ci/azure-doctest-awkward.yml
       - .ci/azure-deploy-awkward.yml
       - .ci/linux-build.sh
       - .readthedocs.yml

include/awkward/Content.h

@@ -31,7 +31,12 @@ namespace awkward {
   /// type. There is a one-to-many relationship from Type to Form.
   class EXPORT_SYMBOL Form {
   public:
-    static FormPtr fromjson(const std::string& data);
+    static FormPtr
+      fromnumpy(char kind,
+                int64_t itemsize,
+                const std::vector<int64_t>& inner_shape);
+    static FormPtr
+      fromjson(const std::string& data);
 
     /// @brief Called by subclass constructors; assigns #has_identities
     /// and #parameters upon construction.