Master does not compile on windows
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.
1. 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);
 }
```
