Changed carbon method naming to be consistent with Carbon itself

src/Carbon.php

@@ -34,7 +34,7 @@ class Carbon extends CarbonBase
      *
      * @return static
      */
-    public function firstOfHalf($dayOfWeek = null)
+    public function startOfHalf($dayOfWeek = null)
     {   
         return $this->setDate($this->year, $this->half * static::MONTHS_PER_HALF - 5, 1)->firstOfMonth($dayOfWeek);
     }
@@ -49,7 +49,7 @@ class Carbon extends CarbonBase
      *
      * @return static
      */
-    public function lastOfHalf($dayOfWeek = null)
+    public function endOfHalf($dayOfWeek = null)
     {   
         return $this->setDate($this->year, $this->half * static::MONTHS_PER_HALF, 1)->lastOfMonth($dayOfWeek);
     }