org: Add a Concepts page.

* doc/org/concepts.org: New file.
* doc/Makefile.am: Add it.
* doc/org/oaut.org: Add anchor.
* doc/org/index.org, doc/org/tut.org: Add links to concepts.org.
* doc/org/spot.css: Set up boxes for implementation details.
* NEWS: Mention the new page.

NEWS

 New in spot 1.99.7a (not yet released)
 
-  Nothing yet.
+  Documentation:
+
+  * There is a new page giving informal illustrations (and extra
+    pointers) for some concepts used in Spot.
+    See https://spot.lrde.epita.fr/concepts.html
 
 New in spot 1.99.7 (2016-01-15)
 

doc/Makefile.am

 ## -*- coding: utf-8 -*-
-## Copyright (C) 2010, 2011, 2013, 2014, 2015 Laboratoire de Recherche et
-## Développement de l'Epita (LRDE).
+## Copyright (C) 2010, 2011, 2013, 2014, 2015, 2016 Laboratoire de
+## Recherche et Développement de l'Epita (LRDE).
 ## Copyright (C) 2003, 2004, 2005 Laboratoire d'Informatique de Paris
 ## 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
 ## Université Pierre et Marie Curie.
@@ -68,6 +68,7 @@ ORG_FILES = \
   org/autfilt.org \
   org/csv.org \
   org/compile.org \
+  org/concepts.org \
   org/dstar2tgba.org \
   org/genltl.org \
   org/hoa.org \

doc/org/index.org

@@ -6,16 +6,17 @@
 Spot is a C++11 library for ω-automata manipulation and model
 checking.  It has the following notable features:
 
-- Support for LTL (several syntaxes supported) and the linear fragment
-  of PSL.
-- Support for ω-automata with arbitrary acceptance condition.
-- Support for transition-based acceptance (state-based acceptance is
+- Support for [[file:concepts.org::#ltl][LTL]] (several syntaxes supported) and
+  [[file:concepts.org::#psl][the linear fragment of PSL]].
+- Support for ω-automata with [[file:concepts.org::#acceptance-condition][arbitrary acceptance condition]].
+- Support for [[file:concepts.org::#trans-acc][transition-based acceptance]] (state-based acceptance is
   supported by a reduction to transition-based acceptance).
 - The automaton parser can read a stream of automata written in any of
   four syntaxes ([[file:hoa.org][HOA]], [[http://spinroot.com/spin/Man/never.html][never claims]], [[http://www.tcs.hut.fi/Software/lbtt/doc/html/Format-for-automata.html][LBTT]], [[http://www.ltl2dstar.de/docs/ltl2dstar.html][DSTAR]]).
 - Several algorithms for formula manipulation including: simplifying
   formulas, testing implication or equivalence, testing
-  stutter-invariance, removing some operators by rewriting, ...
+  stutter-invariance, removing some operators by rewriting, translation
+  to automata...
 - Several algorithms for automata manipulation including: product,
   emptiness checks, simulation-based reductions, minimization of
   weak-DBA, removal of useless SCCs, acceptance-condition

doc/org/oaut.org

@@ -845,6 +845,9 @@ export SPOT_DOTEXTRA='node[style=filled, fillcolor="#ffffa0"] edge[arrowhead=vee
 #+END_SRC
 
 * Statistics
+  :PROPERTIES:
+  :CUSTOM_ID: stats
+  :END:
 
 The =--stats= option takes format string parameter to specify what and
 how statistics should be output.

doc/org/spot.css

@@ -49,3 +49,5 @@ img{max-width:100%}
 .org-hoa-header-uppercase{font-weight:bold;color:#00adad}
 .org-hoa-header-lowercase{color:#00adad}
 .org-hoa-ap-number{color:#d70079}
+.implem{background:#f1f0a6;padding:0.5ex 1ex 0.5ex 1ex;margin:1ex;border-color:#ffe35e;border-style:solid none}
+.implem:before{background:#ffe35e;content:"Implementation detail";padding:.5ex;position:relative;top:0;left:0;font-weight:bold}

doc/org/tut.org

@@ -11,6 +11,9 @@ to see illustrated here.
 If you have difficulties compiling the C++ examples, check out [[file:compile.org][these
 instructions]].
 
+Reading the [[file:concepts.org][concepts page]] might help if you are not familiar with some
+of the objects manipulated here.
+
 * Examples with Shell, Python, and C++
 
 All the following pages show how to perform the same task using the