Improve global and code structure using modules.

Comment and reorganize globals.py
Tests consistently use globals module for OPTions.
Add characterizer as module support.
Modify unit tests to reload new characterizer for ngspice/hspice.
Enable relative and absolute config file arguments so you can run
openram from anywhere on any config file.

compiler/debug.py

@@ -30,7 +30,7 @@ def warning(str):
 
 
 def info(lev, str):
-    OPTS = globals.get_opts()
+    from globals import OPTS
     if (OPTS.debug_level >= lev):
         frm = inspect.stack()[1]
         mod = inspect.getmodule(frm[0])