In 'test_read_structured_binary_oommf_data', made test that checks function detects ascii file correctly. Moved variables 'ascii_files/nodes/bytes' to global variables.
In 'test_read_structured_binary_oommf_data', made test that checks function detects ascii file correctly. Moved variables 'ascii_files/nodes/bytes' to global variables.

fangohr/ovf2vtk,fangohr/ovf2vtk