PMX importer: Two fixes for textured material setup.

I noticed the PMX/PMD importer makes incorrect material setups if the material uses textures.

Fix 1 (722b98e): Don't set alpha=0.0, and use blend type "MULTIPLY".  I experienced the problem when importing the Tohoku-Zunko model created by emer (aka gency).  Her hair should be green, but it actually became white.

Fix 2 (dd2df08): Use texture coordinates "NORMAL" for sphere maps.  Sphere maps were not setup correctly.  You can confirm the problem happens to many MMD models such as mamama's GUMI V3 by and kio-miku.

I made the changes for the master branch, but maybe they can be applied also to the 0.5.0-dev branch.


emer's Tohoku Zunko model: http://blender.rgr.jp/
mamama's GUMI V3 model: http://3xma.blog49.fc2.com/blog-entry-16.html
kio-miku model: http://kiomodel3.sblo.jp/article/29725784.html