[quote date] and [time] need sanity checks

[m4z]

Description

[quote date=N]...[/quote] and[time]N[/time] with huge N, when hitting the preview button in quick preview, can cause 500s ([quote] does this) or break the (quick) preview ([time] does this). (I haven't tested the full preview, posting, or viewing such a post.)

I can't currently access the PHP error message, will provide that later (but it's probably some overflow message).

Reported here: https://www.simplemachines.org/community/index.php?topic=585036.msg4145882#new

Steps to reproduce

1. Post [quote date] with a 20-digit number, hit preview. Witness a 500 error.
2. Post [time] with a 20-digit number, hit preview. Preview won't show, just display "Fetching preview..." indefinitely.

Environment (complete as necessary)

• Version/Git revision: 2.1.4
• Database Type: any?
• Database Version: any?
• PHP Version: any?

Additional information/references

Quick fix for is to limit to 18 characters (or less), that gives us a 10-digit year.