Rewrote press_main_window. Created is_there_next_slice and rewrote are_all_slice_processed.
Rewrote press_main_window. Created is_there_next_slice and rewrote are_all_slice_processed.


Former-commit-id: 7771a2941ae97f78cbcc9d432f5c108f0ce91be7
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox