Explanation comments
Handle -C in the connection pool.  Addresses #559

Parse the options && create the pool, but don't open
any connections.  If the module tries to open a connection
for some purpose, that's OK.  Only one connection will be
opened.
This module is thread-safe.
Mark SQL modules -C safe.  Addresses #559
Make redis modules -C safe.  Addresses #559
Make ldap -C safe.  Addresses #559
Make rest -C safe.  Addresses #559
Make smsotp -C safe.  Addresses #559
If the leading character of a template is '&', it MUST be an attr

Previously parse errors of '&reQET:User-Name were treated as
literal strings.  This is wrong.
Make CHECK_CONFIG_SAFE the default.

All modules are now safe.  Any module which is unsafe will have to
set the flag manually