Use TimingSafeCompare() to compare passwords and password hashes (non-hmac only)

Issue #882
m_spanningtree Accept legacy JOINs from 1202-protocol servers

2.0 accepted JOIN and some pseudoservers might use it
m_spanningtree Translate user mode changes done via FMODE by 1202-protocol servers to MODE
m_spanningtree Drop support for changing user modes with FMODE

This is useless with uuids