Clean up warnings from exception handlers

The exception objects caught are either not referenced at all, or only in
debug builds. This avoids the warnings for the unused variables.

pcbnew/moduleframe.cpp

@@ -366,7 +366,7 @@ const wxString FOOTPRINT_EDIT_FRAME::getLibPath()
 
         return row->GetFullURI( true );
     }
-    catch( const IO_ERROR& ioe )
+    catch( const IO_ERROR& )
     {
         return wxEmptyString;
     }
@@ -409,12 +409,12 @@ void FOOTPRINT_EDIT_FRAME::restoreLastFootprint()
         {
             module = (MODULE*) pcb_io.Parse( pretty );
         }
-        catch( const PARSE_ERROR& pe )
+        catch( const PARSE_ERROR& )
         {
             // unlikely to be a problem, since we produced the pretty string.
             wxLogError( wxT( "PARSE_ERROR" ) );
         }
-        catch( const IO_ERROR& ioe )
+        catch( const IO_ERROR& )
         {
             // unlikely to be a problem, since we produced the pretty string.
             wxLogError( wxT( "IO_ERROR" ) );
@@ -767,7 +767,7 @@ void FOOTPRINT_EDIT_FRAME::updateTitle()
 
             nickname_display = nickname;
         }
-        catch( const IO_ERROR& ioe )
+        catch( const IO_ERROR& )
         {
             // user may be bewildered as to why after selecting a library it is not showing up
             // in the title, we could show an error message, but that should have been done at time