gv-area reports the total cell area of a design.

gv-stats reports area, delay (same as gv-sta) and other metrics of the
netlist.

Verified area against abc to the precision abc reports.

Adjusted gv-sta in a few ways discovered along the way. Methodology was:
change gv-sta to match abc stime to make sure we are not missing
something in abc. Then remove shortcuts/estimates made to match abc and
ensure all information in the liberty file is leveraged. Also fixed a
number of cases where gv-sta errored out. Specific changes:
  - Added scalar bare-literal tie-off support for basic STA.
- Relaxed Liberty monotonicity checking enough to tolerate small ASAP7
characterization noise.
- Added support for Liberty conditional timing arcs: use when when known
scalar constants make an arc provably false; otherwise keep the arc
possible.
- Kept clamping extrapolated negative slew to zero as a physical sanity
bound.