Adds header task to print out all headers (#704)

Will be used to create a generator for IDE's to get include paths.

hal/build.gradle

@@ -202,6 +202,32 @@ model {
                 }
             }
         }
+        getHeaders(Task) {
+            def list = []
+            $.components.each {
+                if (it in NativeLibrarySpec && (it.name == 'halAthena' || it.name == 'halSim')) {
+                    it.sources.each {
+                        it.exportedHeaders.srcDirs.each {
+                            list.add(it)
+                        }
+                    }
+                    it.binaries.each {
+                        it.libs.each {
+                            it.includeRoots.each {
+                                list.add(it)
+                            }
+                        }
+                    }
+                }
+            }
+            list = list.unique(false)
+            doLast {
+                list.each {
+                    print "WPIHEADER: "
+                    println it
+                }
+            }
+        }
     }
 }