Add function to read single xtc frmames.

pygmx/fileio.pxd

@@ -1,4 +1,4 @@
-# from libc.stdio cimport FILE
+from libc.stdio cimport FILE
 
 from utility cimport *
 
@@ -6,11 +6,36 @@ from utility cimport *
 #    ctypedef struct XDR:
 #        pass
 
+cdef extern from "gromacs/fileio/filetypes.h":
+    int fn2ftp(const char *fn)
+
+#cdef extern from "gromacs/fileio/gmx_internal_xdr.h":
+#    ctypedef struct XDR:
+#        pass
+#        
+#    ctypedef enum xdr_op:
+#        XDR_ENCODE = 0
+#        XDR_DECODE = 1
+#        XDR_FREE   = 2
+#
+#    void xdrstdio_create (XDR *__xdrs, FILE *__file, xdr_op __xop)
 
 cdef extern from "gromacs/fileio/gmxfio.h":
 
     ctypedef struct t_fileio:
         pass
+        # FILE           *fp               # the file pointer */
+        # gmx_bool        bRead             # the file is open for reading */
+        # gmx_bool        bDouble           # write doubles instead of floats */
+        # gmx_bool        bReadWrite        # the file is open for reading and writing */
+        # char        *fn                   # the file name */
+        # # XDR         *xdr                  # the xdr data pointer */
+        # int  xdrmode              # the xdr mode */
+        # int          iFTP                 # the file type identifier */
+
+        # t_fileio    *next, *prev          # next and previous file pointers in the linked list */
+        # # tMPI_Lock_t  mtx;                  # content locking mutex. This is a fast lock
+    
 
     void gmx_fio_rewind(t_fileio *fio)