ruby: remove call to curCycle in panic()
The panic() function already prints the current tick value. This call to
curCycle() is as such redundant. Since we are trying to move towards multiple
clock domains, this call will print misleading time.

Ruby: use ClockedObject in Consumer class
Many Ruby structures inherit from the Consumer, which is used for scheduling
events. The Consumer used to relay on an Event Manager for scheduling events
and on g_system_ptr for time. With this patch, the Consumer will now use a
ClockedObject to schedule events and to query for current time. This resulted
in several structures being converted from SimObjects to ClockedObjects. Also,
the MessageBuffer class now requires a pointer to a ClockedObject so as to
query for time.

Ruby Slicc: remove the call to cin.get() function
If I understand correctly, this was put in place so that a debugger can be
attached when the protocol aborts. While this sounds useful, it is a problem
when the simulation is not being actively monitored. I think it is better to
remove this.

Ruby: Remove RubyEventQueue
This patch removes RubyEventQueue. Consumer objects now rely on RubySystem
or themselves for scheduling events.

slicc: cleanup slicc code and make it less verbose

grammar: better encapsulation of a grammar and parsing
This makes it possible to use the grammar multiple times and use the multiple
instances concurrently. This makes implementing an include statement as part
of a grammar possible.

slicc: Change the code generation so that the generated code is easier to read

slicc: have a central mechanism for creating a code_formatter.
This makes it easier to add global variables like protocol

slicc: Pure python implementation of slicc.
This is simply a translation of the C++ slicc into python with very minimal
reorganization of the code. The output can be verified as nearly identical
by doing a "diff -wBur".

Slicc can easily be run manually by using util/slicc