x64 compatibility

[awillinger]

Copy & paste from the Discord:

Current issues when trying to use the plugin on a 64-bit Linux server:

• Despite adding custom items, the "yes" and "no" icons with counters are still present. In current (32-bit) TF2, they are entirely hidden and only the custom items are being displayed
• Once the vote ended, the panel stays open forever, as it seems like the UserMessage has been changed (error in console: expected 6 bytes, got 10)

For the first point:
Expected:
xyz wants to call a vote:
[Title]
[Option 1]
[Option 2]

Actual:
xyz wants to call a vote:
[Title]
[Option 1]
[Option 2]

[Yes] x [No] y

Likely both related to user messages.

[sapphonie]

@nosoop