Master does not compile on windows

[dieterv77]

I ran into issues compiling current master on windows. The problem is with the new pandas/src/numpyhelper.h file

There are two issues there:

1. MSVC does not support "inline" in C (see http://msdn.microsoft.com/en-us/library/z8y1yy88.aspx)
   It does support _inline in C however, which has the intended meaning as far as i can tell.
2. MSVC does not support pointer arithmetic on void *. I fixed that with simple cast.

There's a diff below, it only show how to make it compile on windows, and is not portable. I didn't put this in a pull request because i'm not sure how you would like to make changes that are portable.

diff --git a/pandas/src/numpy_helper.h b/pandas/src/numpy_helper.h
index f5779dd..fe40e8c 100644
--- a/pandas/src/numpy_helper.h
+++ b/pandas/src/numpy_helper.h
@@ -1,30 +1,30 @@
 #include "Python.h"
 #include "numpy/ndarrayobject.h"

-inline int
+_inline int
 is_integer_object(PyObject* obj) {
   return PyArray_IsIntegerScalar(obj);
 }

-inline int
+_inline int
 is_float_object(PyObject* obj) {
   return (PyFloat_Check(obj) || PyArray_IsScalar(obj, Floating));
 }

-inline int
+_inline int
 is_bool_object(PyObject* obj) {
   return (PyBool_Check(obj) || PyArray_IsScalar(obj, Bool));
 }

-inline int
+_inline int
 is_string_object(PyObject* obj) {
   return (PyString_Check(obj) || PyUnicode_Check(obj));
 }

-inline int
+_inline int
 assign_value_1d(PyArrayObject* ap, Py_ssize_t _i, PyObject* v) {
   char *item;
   npy_intp i = (npy_intp) _i;
-  item = PyArray_DATA(ap) + i * PyArray_STRIDE(ap, 0);
+  item = (char *) PyArray_DATA(ap) + i * PyArray_STRIDE(ap, 0);
   return PyArray_DESCR(ap)->f->setitem(v, item, ap);
 }

[wesm]

Cython uses the following macros:

/* inline attribute */
#ifndef CYTHON_INLINE
  #if defined(__GNUC__)
    #define CYTHON_INLINE __inline__
  #elif defined(_MSC_VER)
    #define CYTHON_INLINE __inline
  #elif defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L
    #define CYTHON_INLINE inline
  #else
    #define CYTHON_INLINE
  #endif
#endif

so i'll just use a variant of that. thanks for figuring this out, another user also reported. Proof that I need to get a CI server set up for pandas soon

[wesm]

Can you verify that all works and the test suite passes? I've been building with mingw32 and not MSVC so am not immediately equipped to test

[wesm]

I got the MSVC compiler set up in my VM and verified that all's OK now. Tons of compiler warnings (Py_ssize_t -> int32_t casts) that I need to fix