Added new example program showing new codes features

doc/example_heterogeneous/Makefile

+ifndef CODESBASE
+$(error CODESBASE is undefined, see README.txt)
+endif
+ifndef CODESNET
+$(error CODESNET is undefined, see README.txt)
+endif
+ifndef ROSS
+$(error ROSS is undefined, see README.txt)
+endif
+
+# ross conflates CFLAGS with CPPFLAGS, so use just this one
+override CPPFLAGS += $(shell $(ROSS)/bin/ross-config --cflags) -I$(CODESBASE)/include -I$(CODESNET)/include/codes
+CC = $(shell $(ROSS)/bin/ross-config --cc)
+LDFLAGS = $(shell $(ROSS)/bin/ross-config --ldflags) -L$(CODESBASE)/lib -L$(CODESNET)/lib
+LDLIBS = $(shell $(ROSS)/bin/ross-config --libs) -lcodes-net -lcodes-base 
+
+example: example.c
+
+clean:   
+	rm -f example

doc/example_heterogeneous/README

+This example program shows some features enabled by the new annotation-based
+configuration and mapping APIs in codes-base, as well as support for them in
+codes-net. The example does not exhaustively show all new features added - for
+more details, see configuration.h, codes-mapping.h, and model-net.h in
+codes-net.
+
+Specifically, some features shown are:
+* Use of annotated configuration to initialize three separate network models.
+  Note that they are all the same network model, just with different
+  parameterizations. This includes both the configuration file itself as well as
+  interaction in the code between components with different annotations.
+* Addressing at various levels in both LP type-specific namespaces and
+  model-net namespaces (network id, annotation tuples).
+* The updated registration/configuration sequence in main.

doc/example_heterogeneous/example.conf

+LPGROUPS {
+    ## cluster foo
+    FOO_CLUSTER {
+        repetitions="12";
+        node="1";
+        modelnet_simplenet@foo="1";
+    }
+    FOO_FORWARDERS {
+        repetitions="4";
+        forwarder="1";
+        modelnet_simplenet@foo="1";
+        modelnet_simplenet="1";
+    }
+    ## cluster bar
+    BAR_CLUSTER {
+        repetitions="12";
+        node="1";
+        modelnet_simplenet@bar="1";
+    }
+    BAR_FORWARDERS {
+        repetitions="4";
+        forwarder="1";
+        modelnet_simplenet@bar="1";
+        modelnet_simplenet="1";
+    }
+}
+
+PARAMS {
+    ## ROSS parameters
+    message_size="256";
+
+    ## global modelnet parameters 
+    modelnet_order=("simplenet");
+
+    ## foo cluster network parameters 
+    packet_size@foo="8192";
+    modelnet_scheduler@foo="fcfs";
+    net_startup_ns@foo="1.5";
+    net_bw_mbps@foo="10000";
+
+    ## bar cluster network parameters
+    packet_size@bar="2048";
+    modelnet_scheduler@bar="round-robin";
+    net_startup_ns@bar="3.0";
+    net_bw_mbps@bar="15000";
+
+    ## forwarding network parameters
+    packet_size="4096";
+    modelnet_scheduler="fcfs";
+    net_startup_ns="8.0";
+    net_bw_mbps="5000";
+}
+
+run_params {
+    num_reqs="5";
+    payload_sz="16384";
+}