1. Mouse wheel with Ctrl pressing will zoom in/out the Markdown Web
page;
2. Ctrl+-, Ctrl++ will zoom in/out the Markdown Web page;
3. Ctrl+0 recover the Web page zoom factor to 1.
Add VSettingsDialog to show a settings dialog.
For now, VNote supports setting of language.
Add imcomplete Chinese support.
Signed-off-by: Le Tan <tamlokveer@gmail.com>