Sciter Notes: no extention to exported file name

[ngirard]

Sciter Notes 4.2.7.3.

Steps to reproduce:

• click on "Export note(s) to file"
• type a file name without specifying any extension
• click the Save button

Observed: the file name of the exported file doesn't have any extension

Expected: the file name of the exported file ends with .html.

[ngirard]

The problem still occurs using the latest version (4.3.0.7).