Fix some compile erros (for Java 1.6 compatibility)

Author: jrobinso

IGV.iml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <module type="JAVA_MODULE" version="4">
-  <component name="NewModuleRootManager" inherit-compiler-output="true">
+  <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_6" inherit-compiler-output="true">
     <exclude-output />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />

src/org/broad/igv/feature/GFFFeature.java

@@ -38,7 +38,7 @@
  */
 public class GFFFeature extends BasicFeature {
 
-    List<String> componentAttributes = new ArrayList<>();
+    List<String> componentAttributes = new ArrayList<String>();
 
     public GFFFeature(BasicFeature feature) {
         super(feature);

src/org/broad/igv/track/GFFFeatureSource.java

@@ -110,7 +110,7 @@ public GFFCombiner() {
             gffExons = new ArrayList<BasicFeature>(numElements);
             gffCdss = new LinkedHashMap<String, GFFCdsCltn>(numElements);
             gffUtrs = new ArrayList<BasicFeature>(numElements);
-            gffMrnaParts = new ArrayList<>(numElements);
+            gffMrnaParts = new ArrayList<BasicFeature>(numElements);
 
         }