Adding support for Unicode input files to most text file loaders (BVH and MD5 missing for now).

IrrXML receives memmapped UTF-8 input data now, it's own (faulty) conversion is not used anymore.
aiString's are explicitly UTF-8 now.
Slight refactorings and improvements.
Adding UTF-8/UTF-16 text files for ASE,obj,collada,ac3d. These contain various japanese/chinese character sequences.
Changing assimp_view's node view to display UTF-8 multibyte sequences correctly.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@469 67173fc5-114c-0410-ac8e-9d2fd5bffc1f

code/XFileImporter.cpp

@@ -96,8 +96,10 @@ void XFileImporter::InternReadFile( const std::string& pFile, aiScene* pScene, I
 	if( fileSize < 16)
 		throw new ImportErrorException( "XFile is too small.");
 
+	// in the hope that binary files will never start with a BOM ...
 	mBuffer.resize( fileSize);
 	file->Read( &mBuffer.front(), 1, fileSize);
+	ConvertToUTF8(mBuffer);
 
 	// parse the file into a temporary representation
 	XFileParser parser( mBuffer);