Add missing entries in the Changelog

Changelog

@@ -21,17 +21,40 @@ Open Source Release <next-release>
               it does not introduce additional hypotheses on the program state
 -*  Makefile  [2019/03/07] Do not attempt to install .cmx on bytecode-only
               architectures. Patch by M. Dogguy backported from Debian package
+-   Libc      [2019/03/05] Better specs and removal of half-implemented ifdef
+              that tried to take various POSIX versions into account
 -*  Kernel    [2019/03/05] Better detection of invalid goto in presence of VLA
               (fixes #@499)
+-   GUI       [2019/03/04] Compatibility with lablgtk3 and improved handling of
+              some widgets
+-   ACSL      [2019/03/01] Clarifies which C variables are in scope under a
+              \at(·,L) (#@575)
+-   Libc      [2019/02/26] Ask clang not to warn about unknown FRAMA_C_MODEL
+              attribute when pre-processing frama-c's libc
 -*  Obfuscator [2019/02/26] Obfuscate logic types and logic constructors.
+-*  Inout     [2019/02/21] Fixes operational input on const local initialization
+o   RTE       [2019/02/21] RTE has a static API
+o   Kernel    [2019/02/18] When registering extended ACSL annotations, one
+              must now indicate whether they should have a status.
+o   Kernel    [2019/02/05] Integer API moving closer to Zarith
+-   Eva       [2019/01/19] New warning category for detecting loops without
+              'unroll' directive
+-   Eva       [2019/01/31] Ignore annotations with "no_eva" tag
+-*  ACSL      [2019/01/19] Accept C identifiers that happen to be ACSL keywords
+              in volatile and reads clauses
 -   Eva       [2019/01/10] Improved precision on nested loops (by postponing
               the widening on inner loops according to -eva-widening-period).
+-*  Aorai     [2019/01/04] Fixes #@586: avoid removing the initial state
+              of the automaton
 -   Kernel    [2019/01/03] Add attributes for loop statements to allow
               distinguishing between for, while and dowhile loops.
 -!  Kernel    [2019/01/03] Add statement attributes (sattr) to the AST. They
               are not printed by default, use -kernel-msg-key printer:attrs
 -!  Kernel    [2019/01/03] Improved precision of integer abstract bitwise
               operators.
+o   Kernel    [2018/12/11] New functions for retrieving major and minor version
+-*  Kernel    [2018/12/04] Fixes AST integrity check wrt volatile accesses
+-*  Kernel    [2018/11/21] Fixes #@553 - pretty-printing of basic asm template
 
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 Open Source Release 18.0 (Argon)