CtextBox: Precise function getLines()

Use refreshTextLineArray() for calculation of lines.
Note: 	count of lines will be only returned if CTextBox object
	is initialized with a valid CBox instance,
	otherwise count of 0 lines will be returned!

also remove inline declaration, not needed here


Origin commit data
------------------
Commit: ec83549e50
Author: Thilo Graf <dbt@novatux.de>
Date: 2017-06-15 (Thu, 15 Jun 2017)

src/gui/widget/textbox.cpp

@@ -900,6 +900,16 @@ int CTextBox::getLines(const std::string& text)
 	return count;
 }
 
+int CTextBox::getLines()
+{
+	if (m_cText.empty())
+		return 0;
+
+	refreshTextLineArray();
+
+	return m_nNrOfLines;
+}
+
 int CTextBox::getMaxLineWidth(const std::string& text, Font* font)
 {
 	std::string txt = text;