Make reading DNs more consistent across modules.•••- If the DN contains a new line character then replace it with a
space instead of killing the entire DN in the ssl_gnutls and
ssl_openssl modules.
- Apply the same logic to ssl_mbedtls which previously did not
handle spaces in DNs.
Clean up OnCleanup.•••- Switch to using ExtensionItem::ExtensibleType for the type instead
of TargetTypeFlags.
- Pass the extensible to OnCleanup as an Extensible pointer
instead of a void pointer.
- Call OnCleanup for memberships as well as channels and users.
- Rewrite event documentation to remove outdated references.