- Tests for read_verilog (cover frontends/ast);
- Add tests for read_ilang (new options);

IV frontends
=============

For frontends idea is that you do not do read_verilog but some you are
reading input in different format.
Since most of formats yosys can also read and write you can use plain
verilog write blif for example
and use that as source for this coverage. For liberty files many
examples can be found so that is also in list of tasks

1.
http://scratch.clifford.at/coverage_html/frontends/blif/blifparse.cc.gcov.html
2.
http://scratch.clifford.at/coverage_html/frontends/ilang/ilang_frontend.cc.gcov.html
3.
http://scratch.clifford.at/coverage_html/frontends/json/jsonparse.cc.gcov.html
4.
http://scratch.clifford.at/coverage_html/frontends/liberty/liberty.cc.gcov.html

5. clk2fflogic (104 - 144,180-195 are not covered)
9. memory_nordff(75-101 is not covered)
10. memory_unpack(91-108 is not covered)
12. hierarchy (the coverage from 44% increased to 61,3%)