Prevent crashes in res_xmpp when receiving large messages

Similar to r378287, res_xmpp was marshaling data read from an external source
onto the stack. For a sufficiently large message, this could cause a stack
overflow. This patch modifies res_xmpp in a similar fashion to res_jabber by
removing the stack allocation, as it was unnecessary.

(issue ASTERISK-20658)
Reported by: wdoekes
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Merged revisions 378409 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@378410 f38db490-d61c-443f-a65b-d21fe96a405b
Prevent exhaustion of system resources through exploitation of event cache

This patch changes res_xmpp to no longer cache events under certain circumstances.

(issue ASTERISK-20175)
Reported by: Russell Bryant, Leif Madsen, Joshua Colp
Tested by: kmoore
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Merged revisions 378411 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@378412 f38db490-d61c-443f-a65b-d21fe96a405b
Add aliases to the Directory.

This is an interesting feature that allows additional strings to be used to
search the Directory, primarily intended to be used with nicknames, but could
be used with affiliations and the like.  Because the name field is used in
more than one place (such as email notifications), it is important that these
additional strings not be placed in the name field, but be specified
separately.

Review: https://reviewboard.asterisk.org/r/2244/


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@378414 f38db490-d61c-443f-a65b-d21fe96a405b