add test for "ORA-01458: invalid length inside variable character string"
add TestSelectBind to ./oracle, too
Modify number data lengths: fixes #17

There is the mechanism for using native ints and floats, but didn't
worked when I tried, so it is switched off (dataInts=nil, dataFloats=nil).
But the Int64VarType's size were still set to 8, not C.sizeof_OCINumber (22).
This is fixed now.