wxStringTokenizer usage cleanup.

1) Always be explicit about what the delimiters are
2) If space is a delimiter, we probably want to skip
empty fields (wxTOKEN_STRTOK)
3) If space is not a delimiter, we often need to
trim the resultant tokens
4) Be more lenient about \t\r\n (and when they are
included, include them in the same order)

kicad/cli/command_sch_export_plot.cpp

@@ -143,10 +143,10 @@ int CLI::SCH_EXPORT_PLOT_COMMAND::doPerform( KIWAY& aKiway )
 
     std::vector<wxString> pages;
     wxString              pagesStr = From_UTF8( m_argParser.get<std::string>( ARG_PAGES ).c_str() );
-    wxStringTokenizer     tokenizer( pagesStr, "," );
+    wxStringTokenizer     tokenizer( pagesStr, ",", wxTOKEN_STRTOK );
 
     while( tokenizer.HasMoreTokens() )
-        pages.push_back( tokenizer.GetNextToken().Trim() );
+        pages.push_back( tokenizer.GetNextToken().Trim( wxString::both) );
 
     std::unique_ptr<JOB_EXPORT_SCH_PLOT> plotJob;