Merge pull request #29 from jiafulow/prepare-v031

Major changes in IO classes
Corrected init() to return error.
Re-enabled trigger tower option in PatternMatcher class
Updated drawer scripts

One hundred more lines to draw tt27 intervals in drawer_stubs.py

Minor fixes in drawer_pileup.py

Minor fixes in drawer_amsim.py

Fixes in drawer_patternbank.py

Fixes in drawer_roads.py
Explicitly apply floor() function in SuperstripArbiter