Testing problems:

1.scc_feedback - Feedback is detected not in each case(with different
options).
2.splice/splice_port - No any changes in the dump after splice -port
command.
3.test_cell/test_cell_macc - ERROR: Assert `port_declared == true'
failed in kernel/rtlil.cc:1352.

Add tests for splitnets command
Expand coverage for trace command
Expand coverage for splice command (tests for options)
Expand coverage for scc command (different loops)
Expand coverage for rename command
Change test for passes/techmap/deminout
Update test for 'dff2dffe -direct' command
Add test for 'dffsr2dff' command
Expand coverage for iopadmap command