When build.core is not defined, fall back to "arduino". Fixes #2635

Author: Federico Fissore

arduino-core/src/processing/app/BaseNoGui.java

@@ -688,7 +688,7 @@ static public void onBoardOrPortChange() {
     // Add library folder for the current selected platform
     TargetPlatform targetPlatform = getTargetPlatform();
     if (targetPlatform != null) {
-      String core = getBoardPreferences().get("build.core");
+      String core = getBoardPreferences().get("build.core", "arduino");
       if (core.contains(":")) {
         String referencedCore = core.split(":")[0];
         TargetPlatform referencedPlatform = getTargetPlatform(referencedCore, targetPlatform.getId());

arduino-core/src/processing/app/debug/Compiler.java

@@ -426,7 +426,7 @@ private PreferencesMap createBuildPreferences(String _buildPath,
     TargetPlatform targetPlatform = BaseNoGui.getTargetPlatform();
     TargetPlatform corePlatform = null;
     PreferencesMap boardPreferences = BaseNoGui.getBoardPreferences();
-    String core = boardPreferences.get("build.core");
+    String core = boardPreferences.get("build.core", "arduino");
     if (core.contains(":")) {
       String[] split = core.split(":");
       core = split[1];

arduino-core/src/processing/app/helpers/PreferencesMap.java

@@ -319,4 +319,12 @@ public boolean putBoolean(String key, boolean value) {
     return new Boolean(prev);
   }
 
+  public String get(String key, String defaultValue) {
+    String value = get(key);
+    if (value != null) {
+      return value;
+    }
+    return defaultValue;
+  }
+
 }