Juno build system, labels, and skeleton scheduler

This includes some refactoring and new feature for Juno:

• An improved build system for Juno which can be used in build scripts (see juno_samples for examples; matmul currently does not compile but the simple3 example can fully compile and run by just invoking cargo run from that directory) along with a juno! macro for importing Juno code into Rust (there is currently a known issue where the empty product is not being generated by the Hercules RT proc macro and so this needs to be included manually in Rust for the moment)
• Labels which are tracked through semantic analysis and code generation to produce a data structure which tracks the set of labels and the associated NodeIDs in the Hercules IR (along with some information on what structure was labeled, i.e. if a label was on a loop we also make note of the header of the loop)
• An initial skeleton of the scheduler, this will likely be completely rewritten but currently provides the ability to specify partitions based on the initial labels.

hercules_cg/src/manifest.rs

@@ -2,6 +2,7 @@ extern crate serde;
 
 extern crate hercules_ir;
 
+use std::collections::BTreeSet;
 use std::iter::once;
 
 use self::serde::Deserialize;
@@ -113,6 +114,24 @@ impl Manifest {
                 SType::Product(partition.returns.iter().map(|(ty, _)| ty.clone()).collect())
             }))
     }
+
+    pub fn transitive_closure_type_set(type_set: BTreeSet<SType>) -> BTreeSet<SType> {
+        let mut closure = BTreeSet::new();
+        let mut workset: BTreeSet<&SType> = type_set.iter().collect();
+
+        while let Some(ty) = workset.pop_last() {
+            match ty {
+                SType::Product(fields) => workset.extend(fields),
+                SType::ArrayRef(elem) => {
+                    workset.insert(elem);
+                }
+                _ => {}
+            }
+            closure.insert(ty.clone());
+        }
+
+        closure
+    }
 }
 
 impl PartitionManifest {