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/ObjFileParser.cpp

@@ -452,10 +452,8 @@ void ObjFileParser::getMaterialLib()
 	}
 
 	// Import material library data from file
-	size_t size = pFile->FileSize();
-	std::vector<char> buffer( size + 1 );
-	buffer[ size ] = '\0';
-	pFile->Read( &buffer[ 0 ], sizeof( char ), size );
+	std::vector<char> buffer;
+	BaseImporter::TextFileToBuffer(pFile,buffer);
 	io->Close( pFile );
 
 	// Importing the material library