OpenVPN options dependencies are not respected

[pierre.gaufillet@…]

After the resolution of the ticket #219, there is still a problem: dependencies between options don't work as they should. Indeed, they would only work if the options are both on the same page.

The attached patch gives a first prototype of solution to this problem using tabs. But OpenVPN has numerous options, and tabs are therefore too long to be really useable.

A second approach would consist in adding "Additional Fields" support to tabs.