sieve/ : prefer reentrant time functions

-- Replace calls to localtime() and gmtime() with calls to localtime_r()
   and gmtime_r(), so that libcyrus_sieve can be used in multithreaded
   applications.
Corrected gmtoff_of usage and fix crash caused by commit 0be6827.
Bug#3848 lib/charset/aliases.txt: add latin1 as alias of iso-9959-1
Hope to get rid of these segfaults once and for all
Update verify_cb() in ctl_mboxlist
sieve/sieve.y: fix comment

In "vu should call yyerror" vu is supposed to mean verify_utf8, but
here verify_address (=va) is the function, who would call yyerror.
Fix order and maximum parameters number in mbox events
configure.ac: print in the summary if GSSAPI and KRB4 were found

... instead of printing the information at STDERR.  This is consistent
with the procedure to use in the summary at the end of ./configure to
say what was actually activated.
sieve/bc_eval.c: write commands' bytecode in comment

... right after the bytecode
sieve/bc_e*.c: fix typos in comment
[mboxevent]: Fix issues.k.o/3705, segmentation fault upon DELETEACL command
Originally from issues.kolab.org #3695:

  - Ensure event notifications hold the correct uri parameter for shared folders
  - Test mboxname_to_parts function as extensively as possible, rather than stabby hit-and-miss
Index Extension - Fix backward compatibility