fixed function name to unset

Author: dongasai

src/Input/Parser.php

@@ -249,11 +249,11 @@ protected function register(Parameter $param)
     }
 
     /**
-     * unRegister a new argument/option.
+     * unset a registered argument/option.
      *
      * @param string $name
      */
-    public function unRegister($name)
+    public function unset($name)
     {
         unset($this->_values[$name], $this->_arguments[$name], $this->_options[$name]);
 

tests/Input/CommandTest.php

@@ -261,12 +261,12 @@ public function test_bind()
         $this->assertNull($c->app());
     }
 
-    public function test_unregister()
+    public function test_unset()
     {
         $c = $this->newCommand();
         $this->assertCount(3, $c->allOptions());
         $this->assertArrayHasKey('verbosity', $c->allOptions());
-        $c->unRegister('verbosity');
+        $c->unset('verbosity');
         $this->assertCount(2, $c->allOptions());
         $this->assertArrayNotHasKey('verbosity', $c->allOptions());
     }