GLATEventCube::maxrad returns 0 is sky direction lies outside event cube.

The GLATEventCube::maxrad now returns 0 if a sky direction lies outside the event cube. Before, the method has returned a positive radius, which led to an incorrect normalization of the PSF for sources lying outside the event cube.
Reformat code and correct bug in copy_members().

The member m_last_index1 was copied twice and m_last_index2 was never copied in copy_members(). Now both members are copied correctly.