python: Move more code into m5.util allow SCons to use that code.

Get rid of misc.py and just stick misc things in __init__.py
Move utility functions out of SCons files and into m5.util
Move utility type stuff from m5/__init__.py to m5/util/__init__.py
Remove buildEnv from m5 and allow access only from m5.defines
Rename AddToPath to addToPath while we're moving it to m5.util
Rename read_command to readCommand while we're moving it
Rename compare_versions to compareVersions while we're moving it.

--HG--
rename : src/python/m5/convert.py => src/python/m5/util/convert.py
rename : src/python/m5/smartdict.py => src/python/m5/util/smartdict.py

src/python/m5/simulate.py

@@ -40,6 +40,9 @@ import SimObject
 import ticks
 import objects
 
+# define a MaxTick parameter
+MaxTick = 2**63 - 1
+
 # The final hook to generate .ini files.  Called from the user script
 # once the config is built.
 def instantiate(root):