[Bf-python] getTangent missing in the 2.5x api

[Thomas Egenhofer]

Hello everyone,

i tried to speed up an exporter for blender that was rewritten for 2.5x
because it took 15minutes and more to export my models. it turned out
that it spend amlost all of the time with hand-written tangent and
bitangent calculation in python.

researching i found that blender 2.4x had a getTangent() call.
blender 2.5x still has all code in c to calculate a tangent given a
vertex index and uv-set. but it is not exposed in the python api.

many game engines and files require the tangent information for
normalmapping, so it is vital for most exporters.

any chance to get the getTangent call back in? it would make writing
exporters not only easier, but also cutting export times from hours to
seconds (on big models)

the code is in
source/blender/blenlib/intern/math_geom.c starting line 2300

the getTangent call was in 
http://www.blender.org/documentation/249PythonDoc/Mesh.Mesh-class.html