Fix crash on initialization when arrays are not allocated.

Added checks for m_IsAllocated before attempting to assign data to
the internal array.
Removing the -Wall compiler flag for GCC and Clang. Just too many warnings from ITK
and Qt.
Fix some possible crashing bugs with the logic
Rewrite class to mimic the actual Vtk source code

The class was rewritten using code lifted from the Vtk project so that the class
should be able to read either CELL_DATA or POINT_DATA in any order. We are
just reading the SCALARS and VECTORS at the moment (both need to be tested). The
code logic uses the same looping style and low leve std::streams classes that
Vtk uses in its implementation.
Fix parsing errors when CELL_DATAT is present.

Fixed error where the correct attribute matrix was not being used
when reading the CELL_DATA sections.