Use standard library style members of wxArrayString (and wxString) ...

... which will make it easier to change the types of those containers to
std::vectors of other string-like classes

for wxString,

IsEmpty => empty
Clear => clear
Alloc => reserve

for wxArrayString,

Count => size
GetCount => size
IsEmpty => empty
Add => push_back
Clear => clear
Empty => clear
Sort => std::sort (only with default comparator)
SetCount => resize
Last => back
Item => operator []
Alloc => reserve

src/HelpText.cpp

@@ -307,7 +307,7 @@ wxString HelpText( const wxString & Key )
    wxString Text;
    Text = HelpTextBuiltIn( Key );
 
-   if( !Text.IsEmpty())
+   if( !Text.empty())
       return LinkExpand( Text );
 
    // Perhaps useful for debugging - we'll return key that we didn't find.