Eeschema: fix remapping bug on windows builds.

The Windows drive specifier C: was being interpreted as a valid URL by
wxURI which was performing a URL comparison instead of a file comparison
which always failed in LIB_TABLE_BASE::FindRowByURI().  Change test for
URI to search string for "://" to determine if the comparison should be
a URI (string) comparison or a file (wxFileName) comparison.

Don't run final rescue unless the user performs the remapping.

common/lib_table_base.cpp

@@ -338,9 +338,7 @@ const LIB_TABLE_ROW* LIB_TABLE::FindRowByURI( const wxString& aURI )
         {
             wxString tmp = cur->rows[i].GetFullURI( true );
 
-            wxURI uri( tmp );
-
-            if( uri.HasScheme() )
+            if( tmp.Find( "://" ) != wxNOT_FOUND )
             {
                 if( tmp == aURI )
                     return &cur->rows[i];  // found as URI

eeschema/dialogs/dialog_symbol_remap.cpp

@@ -64,10 +64,19 @@ DIALOG_SYMBOL_REMAP::DIALOG_SYMBOL_REMAP( SCH_EDIT_FRAME* aParent ) :
 
 void DIALOG_SYMBOL_REMAP::OnRemapSymbols( wxCommandEvent& aEvent )
 {
+    SCH_EDIT_FRAME* parent = dynamic_cast< SCH_EDIT_FRAME* >( GetParent() );
+
+    wxCHECK_RET( parent != nullptr, "Parent window is not type SCH_EDIT_FRAME." );
+
     wxBusyCursor busy;
 
     backupProject();
 
+    // Ignore the never show rescue setting for one last rescue of legacy symbol
+    // libraries before remapping to the symbol library table.  This ensures the
+    // best remapping results.
+    parent->RescueLegacyProject( false );
+
     // The schematic is fully loaded, any legacy library symbols have been rescued.  Now
     // check to see if the schematic has not been converted to the symbol library table
     // method for looking up symbols.

eeschema/files-io.cpp

@@ -343,11 +343,6 @@ bool SCH_EDIT_FRAME::OpenProjectFiles( const std::vector<wxString>& aFileSet, in
         // Convert old projects over to use symbol library table.
         if( schematic.HasNoFullyDefinedLibIds() )
         {
-            // Ignore the never show rescue setting for one last rescue of legacy symbol
-            // libraries before remapping to the symbol library table.  This ensures the
-            // best remapping results.
-            RescueLegacyProject( false );
-
             DIALOG_SYMBOL_REMAP dlgRemap( this );
 
             dlgRemap.ShowQuasiModal();