Add .vex to extensions

[fltv]

using .vex in the latest version of VSCode did not work until adding this change.

[melMass]

Thanks

using .vex in the latest version of VSCode did not work until adding this change.

That's because the extension for vex files is either .h or .vfl, in vscode you can set the file association in your user settings to vex too if you want, that said I don't mind adding it by default.

I have another unpublished update that changes a lot so I probably won't merge this PR directly, but I'm keeping it open as a reminder. I'll try to make the new release this week.

[fltv]

I thought I remembered reading somewhere that .vex was also standard. I could be wrong, but all my vex files are .vex 😅
Reading the docs again, as it turns out, .vex is used for the compiled .vfl files.

Probably best to ignore me on this one for the sake of confusion. I have some renaming to do.