Simplify models during import

[AttilaFarkas]

It would be a good option if we can simplify the models during the import because now its a really time consuming process to open, simplify and save big models. If we use the reference model option the assembly file also will be big because it contains the whole imported data.

For example I've got a STP file which is 517 Mb, the assembly file which contains the referenced STP file is 788 Mb and it takes hours until I've got the final simplified part.

Generally the whole process can be much faster, more simple and the size of the generated files can be much smaller.