Fix issues involving math.tau

[Denneisk]

Many users have been complaining about the number extension suddenly not working. This is because some servers don't have math.tau defined on them for whatever reason. This PR presents a twofold solution:

1. It sets a fallback for math.tau when it is undefined.
2. It ensures any future invalid constants will not cause extensions to fail loading.

Changes:

• Add fallback for math.tau
• Change error in E2Lib.registerConstant to use WireLib.Notify instead so invalid constants don't break the extension.
• Added some context to the errors in E2Lib.registerConstant (This functionality should probably be moved to its own function)
• Added timeout for WireLib.Notify "nudges" on the client

Updated error form (note E2 executes extension files twice):

[Denneisk]

Messed up something with the git history whatever

[Grocel]

This is because some servers don't have math.tau defined on them for whatever reason.

That's because GMod updates are optional on servers, so servers are outdated sometimes. The math.tau constant was added in last main update. Rubat's tip toeing around net compatibility makes it possible that server could be outdated by 2+ years and still be able to connect to. Good luck accounting for those servers in addon code on the long run.