Removed warnings when compiling using MSVC/Mingw under 64bit Windows
BUG: changed index types to Py_ssize_t to use 64-bit indexes on 64 bit machines.

Compiles on Windows-7 64bit with just a few warnings remaining (of initially hundreds) that I cannot fix since they seem to be upstream in cython.

C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -ID:\Python27\lib\site-packages\numpy\core\include -ID:\Python27\include -ID:\Python27\PC /Tcpandas\src\tseries.c /Fobuild\temp.win-amd64-2.7\Release\pandas\src\tseries.obj
tseries.c
pandas\src\tseries.c(13717) : warning C4244: '+=' : conversion from 'Py_ssize_t' to 'long', possible loss of data
pandas\src\tseries.c(13727) : warning C4244: '+=' : conversion from 'Py_ssize_t' to 'long', possible loss of data
pandas\src\tseries.c(17890) : warning C4244: 'function' : conversion from 'Py_ssize_t' to 'int', possible loss of data
pandas\src\tseries.c(23257) : warning C4244: 'function' : conversion from '__int64' to 'long', possible loss of data
pandas\src\tseries.c(26305) : warning C4267: '=' : conversion from 'size_t' to 'char', possible loss of data
pandas\src\tseries.c(26316) : warning C4267: 'initializing' : conversion from 'size_t' to 'int', possible loss of data
C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\amd64\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:D:\Python27\libs /LIBPATH:D:\Python27\PCbuild\amd64 /EXPORT:init_tseries build\temp.win-amd64-2.7\Release\pandas\src\tseries.obj /OUT:build\lib.win-amd64-2.7\pandas_tseries.pyd /IMPLIB:build\temp.win-amd64-2.7\Release\pandas\src_tseries.lib /MANIFESTFILE:build\temp.win-amd64-2.7\Release\pandas\src_tseries.pyd.manifest
tseries.obj : warning LNK4197: export 'init_tseries' specified multiple times; using first specification
   Creating library build\temp.win-amd64-2.7\Release\pandas\src_tseries.lib and object build\temp.win-amd64-2.7\Release\pandas\src_tseries.exp
C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin\x64\mt.exe -nologo -manifest build\temp.win-amd64-2.7\Release\pandas\src_tseries.pyd.manifest -outputresource:build\lib.win-amd64-2.7\pandas_tseries.pyd;2
cythoning pandas\src\sparse.pyx to pandas\src\sparse.c
building 'pandas._sparse' extension
C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\amd64\cl.exe /c /nologo /Ox /MD /W3 /GS- /DNDEBUG -ID:\Python27\lib\site-packages\numpy\core\include -ID:\Python27\include -ID:\Python27\PC /Tcpandas\src\sparse.c /Fobuild\temp.win-amd64-2.7\Release\pandas\src\sparse.obj
sparse.c
pandas\src\sparse.c(4846) : warning C4244: '+=' : conversion from 'Py_ssize_t' to 'long', possible loss of data
pandas\src\sparse.c(7557) : warning C4244: '+=' : conversion from 'Py_ssize_t' to 'long', possible loss of data
pandas\src\sparse.c(16613) : warning C4244: 'function' : conversion from '__int64' to 'long', possible loss of data
pandas\src\sparse.c(19732) : warning C4267: '=' : conversion from 'size_t' to 'char', possible loss of data
pandas\src\sparse.c(19743) : warning C4267: 'initializing' : conversion from 'size_t' to 'int', possible loss of data
C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\BIN\amd64\link.exe /DLL /nologo /INCREMENTAL:NO /LIBPATH:D:\Python27\libs /LIBPATH:D:\Python27\PCbuild\amd64 /EXPORT:init_sparse build\temp.win-amd64-2.7\Release\pandas\src\sparse.obj /OUT:build\lib.win-amd64-2.7\pandas_sparse.pyd /IMPLIB:build\temp.win-amd64-2.7\Release\pandas\src_sparse.lib /MANIFESTFILE:build\temp.win-amd64-2.7\Release\pandas\src_sparse.pyd.manifest
