C#: revert XMLComment -> XmlComment change to avoid name conflict

Author: erik-krogh

csharp/ql/lib/semmle/code/csharp/XML.qll

@@ -72,7 +72,7 @@ class XmlParent extends @xmlparent {
   XmlElement getAChild(string name) { xmlElements(result, _, this, _, _) and result.hasName(name) }
 
   /** Gets a comment that is a child of this XML parent. */
-  XmlComment getAComment() { xmlComments(result, _, this, _) }
+  XMLComment getAComment() { xmlComments(result, _, this, _) }
 
   /** Gets a character sequence that is a child of this XML parent. */
   XmlCharacters getACharactersSet() { xmlChars(result, _, this, _, _, _) }
@@ -325,7 +325,7 @@ deprecated class XMLNamespace = XmlNamespace;
  * <!-- This is a comment. -->
  * ```
  */
-class XmlComment extends @xmlcomment, XmlLocatable {
+class XMLComment extends @xmlcomment, XmlLocatable {
   /** Gets the text content of this XML comment. */
   string getText() { xmlComments(this, result, _, _) }
 
@@ -336,9 +336,6 @@ class XmlComment extends @xmlcomment, XmlLocatable {
   override string toString() { result = this.getText() }
 }
 
-/** DEPRECATED: Alias for XmlComment */
-deprecated class XMLComment = XmlComment;
-
 /**
  * A sequence of characters that occurs between opening and
  * closing tags of an XML element, excluding other elements.