Allow tab characters with cmode +c

[fidsah]

Currently, messages containing the tab character(ASCII character 9) are prevented from being transmitted to a channel by the current check for ASCII characters less than 31. This patch is intended to preserve the intent of stopping control codes from being transmitted to a channel, while allowing messages containing the tab character to be transmitted.

[rscs]

Hi, @fidsah ... can you tell us more how this request came about? What's the proposed use case?

Tab is a well-documented ASCII control character. In fact, I can't find a single site that DOESN'T consider it a control character.

Examples:

• https://en.wikipedia.org/wiki/Control_character#In_ASCII
• https://www.aivosto.com/articles/control-characters.html
• http://ascii-table.com/control-chars.php
• https://ascii.cl/control-characters.htm
• http://jkorpela.fi/chars/c0.html

[github-actions[bot]]

Stale pull request message

[eaescob]

Closing this PR as it hasn't had activity in quite some time. @fidsah if you want to re-open this, please create an issue to start discussion instead. Thanks!