Sign text has no length limitation

Sign text has no limitation on length. This is an easy-to-exploit denial-of-service attack vector due to the performance issues that result when large text payloads are found on signs.

Steps to reproduce:
1. Fill a sign with a character, for example "a"
2. Press ctrl+a and ctrl+c to copy
3. Press ctrl+v a bunch of times. Notice that your hand movement starts to lag in the background.

In addition, the game will temporarily freeze when rejoining the game in the area containing the affected sign.