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/commands/BatchEvalCommand.cpp

@@ -64,7 +64,7 @@ bool BatchEvalCommand::Apply(const CommandContext & context)
    bool bResult = Batch.ApplyCommandInBatchMode(friendly, cmdName, cmdParams, &context);
    // Relay messages, if any.
    wxString Message = Batch.GetMessage();
-   if( !Message.IsEmpty() )
+   if( !Message.empty() )
       context.Status( Message );
    return bResult;
 }