Move max_time and progress_interval parameters to the Root

Move max_time and progress_interval parameters to the Root
object and get rid of the ParamContext that each used to have.

python/m5/objects/Root.py:
    Add max_time and progress_interval to the Root object
sim/root.cc:
    Add max_time and progress_interval to the Root object.  These
    parameters used to be in their own contexts in sim_events.cc
sim/sim_events.cc:
    Get rid of the ParamContext for max cycles and the progress
    event.  Move the functionality to the Root object
sim/sim_events.hh:
    Move ProgressEvent declaration to the header so that it can
    be used in other files.

--HG--
extra : convert_revision : ff664b806855e8eb9201b8a25392aa53204464f0