Made shader property flags interace dynamic, to avoid spelling mistakes and mismatches on format update.

Fixed name error of Facegen Detail Map property, causing it not to be exported. Added condition to not export normals when using a face tint (as done in face meshes).

Fixed spelling error in slsf1 'enviroment mapping' shader flag which caused incorrect import of the environment mapping flag (probably export too, but couldn't test that)

Allows for improved maintainability & extensibility.

emissive alpha value.

support. changed material normals check for mesh export.
fix bug on export for bdfadenode for skyrim model.

frome objects.

Split out the various classes from the single UI file into multiple
modules to increase code cohesion. Added check for Mesh type for
partition panel rendering

niftools.object menu

settings. Unified import and export error classes to nif_utils.NifError
for sanity sake. 

current nif files

renamed a few variables