Adding seek() and size() functions to SD File class.

Author: damellis

libraries/SD/File.cpp

@@ -51,6 +51,14 @@ void File::flush() {
   SD.file.sync();
 }
 
+boolean File::seek(uint32_t pos) {
+  return SD.file.seekSet(pos);
+}
+
+uint32_t File::size() {
+  return SD.file.fileSize();
+}
+
 void File::close() {
   SD.file.close();
 }

libraries/SD/SD.h

@@ -33,6 +33,8 @@ class File : public Stream {
   virtual int peek();
   virtual int available();
   virtual void flush();
+  boolean seek(uint32_t pos);
+  uint32_t size();
   void close();
   operator bool();
 };