fixed typo

m_canMipMap -> m_canMipmap
allow querying the size of the various arrays
only so automatic smoothing if there are no normals (yet)

for compatibilities sake, [model] should do smoothing (0.5), even
if the user did not request it explicitely.
otoh, if the model already contains normals information, we probably
don't want that.
so we only apply an auto-smooth if the model doesn't yet have any normals.
fixed canvas-sizes and alignments
added missing help-patches to install

[trapezoid], [pix_equal]