use chronological order for E-ACSL references

doc/userman/userman.bib

@@ -110,15 +110,7 @@ note={Extended version of \cite{sefm12}},
   note   = {\url{https://frama-c.com/fc-plugins/e-acsl.html}},
 }
 
-@inproceedings{secureflow1,
-  author = {Gerg\"o Barany and Julien Signoles},
-  title  = {{Hybrid Information Flow Analysis for Real-World C Code}},
-  booktitle  = {International Conference on Tests and Proofs (TAP'17)},
-  year   = 2017,
-  month  = jul,
-}
-
-@phdthesis{secureflow2,
+@phdthesis{secureflow1,
   author = {Mounir Assaf},
   title  = {{From Qualitative to Quantitative Program Analysis:
  Permissive Enforcement of Secure Information Flow}},
@@ -127,6 +119,14 @@ note={Extended version of \cite{sefm12}},
   school = {Universit\'e Rennes 1},
 }
 
+@inproceedings{secureflow2,
+  author = {Gerg\"o Barany and Julien Signoles},
+  title  = {{Hybrid Information Flow Analysis for Real-World C Code}},
+  booktitle  = {International Conference on Tests and Proofs (TAP'17)},
+  year   = 2017,
+  month  = jul,
+}
+
 @inproceedings{ltest,
   author    = {Micha{\"{e}}l Marcozzi and
                S{\'{e}}bastien Bardin and