CComponentsHeader: fix centering of header title

Origin commit data
------------------
Commit: 178bf6f596
Author: Thilo Graf <dbt@novatux.de>
Date: 2017-05-10 (Wed, 10 May 2017)

src/gui/components/cc_frm_header.cpp

@@ -581,7 +581,7 @@ void CComponentsHeader::initCaption()
 
 		//set alignment of text item in dependency from text alignment
 		if (cch_caption_align == CTextBox::CENTER)
-			cch_text_x = CC_CENTERED;
+			cch_text_x = width/2 - cc_text_w/2;
 
 		//assign general properties
 		cch_text_obj->setDimensionsAll(cch_text_x, cch_items_y, cc_text_w, height);