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/AudacityLogger.cpp

@@ -71,7 +71,7 @@ void AudacityLogger::DoLogText(const wxString & str)
       wxMutexGuiEnter();
    }
 
-   if (mBuffer.IsEmpty()) {
+   if (mBuffer.empty()) {
       wxString stamp;
 
       TimeStamp(&stamp);