Binary STL write

[neurolabusc]

The writeMesh provides an option to create either binary or ASCII output. For the STL output, the default ASCII output functions (albeit slow and large files), while writing a binary STL fails (creating just 12 bytes solid ascii):

from itkwasm_image_io import imread, imwrite
from itkwasm_mesh_io import meshread, meshwrite
mesh = meshread('brain.stl')
# n.b. output STL ASCII ~4 times larger than binary STL
meshwrite(mesh, 'brainSTLa.stl')
# only creates 12-byte header for binary STL output
meshwrite(mesh, 'brainSTL.stl', {'binary': True})