Added Chunk Support

Author: bayareawebpro

README.md

@@ -58,7 +58,7 @@ public function download(Request $request)
 
 #### Extended Options
 ```
-SimpleCsv::import($path = '/some/file.csv', $delimiter = ",", $enclosure = "\"", $escape = "\\");
+SimpleCsv::import($path = '/some/file.csv', $callback = function, $chunk = 500, $delimiter = ",", $enclosure = "\"", $escape = "\\");
 SimpleCsv::export($collection, $delimiter = ",", $enclosure = "\"", $escape = "\\");
 ```
 
@@ -115,6 +115,15 @@ DB::transaction(function(){
 });
 ```
 
+Expose chunk callback to generator allowing lower memory consumption for large files:
+```
+DB::transaction(function(){
+    SimpleCsv::import(storage_path('table.csv'), function($chunk){
+       DB::insert($chunk->toArray());
+    }, 1000);
+});
+```
+
 #### DebugBar Timeline Results:
 
 | Operation | Chunk  | Total Entries | Total Memory | Framework Memory | Actual Memory | Total Time | Framework Time | Actual Time |