Method export_progress

src/file_progress.cpp:122–127

	}

	void file_progress::export_progress(vector<std::int64_t, file_index_t>& fp)
	{
		INVARIANT_CHECK;
		fp.resize(m_file_progress.size(), 0);
		std::copy(m_file_progress.begin(), m_file_progress.end(), fp.begin());
	}

	void file_progress::clear()
	{