Revert "protocol/ngircd: Ignore non-# channels in m_join(), m_part() and m_chaninfo()"

This reverts commit 349b35c4821d1b9360f5789dd8bd90e24bb44fe6.
protocol: use VALID_GLOBAL_CHANNEL_PFX() where appropriate
protocol: add VALID_CHANNEL_PFX() and use it in some places
alis: add support for searching +channels
operserv/sqline: try to sqline any channel type atheme can conceptually recognize