Merge: nitiwiki: external highlighter

This is a cleaned up version of what is currently doing the code highlighting and the table in the deployed http://nitlanguage.org

The basic idea here is to delegate the job to some other program. The program has to be configured in the config.ini under the key `wiki.highlighter`

This approach, while not pure nit, makes it quite easy to use whatever highlighter program the user prefer with whatever options (instead of hard-coding a specific external program in the nit source code).

An advanced way is to delegate to a shell script that checks arguments then dispatches to a real program.

ping maintainer: @Morriar

Pull-Request: #1701
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>

diff --combined src/testing/testing_doc.nit
index 82518da,458e2c6..6bd8f0b
--- 1/src/testing/testing_doc.nit
--- 2/src/testing/testing_doc.nit
+++ b/src/testing/testing_doc.nit
@@@ -290,11 -290,8 +290,8 @@@ private class NitunitDecorato
        var executor: NitUnitExecutor
  
        redef fun add_code(v, block) do
-               var code = code_from_block(block)
-               var meta = "nit"
-               if block isa BlockFence and block.meta != null then
-                       meta = block.meta.to_s
-               end
+               var code = block.raw_content
+               var meta = block.meta or else "nit"
                # Do not try to test non-nit code.
                if meta != "nit" then return
                # Try to parse code blocks
@@@ -321,26 -318,6 +318,6 @@@
                # Add it to the file
                executor.blocks.last.append code
        end
- 
-       # Extracts code as String from a `BlockCode`.
-       fun code_from_block(block: BlockCode): String do
-               var infence = block isa BlockFence
-               var text = new FlatBuffer
-               var line = block.block.first_line
-               while line != null do
-                       if not line.is_empty then
-                               var str = line.value
-                               if not infence and str.has_prefix("    ") then
-                                       text.append str.substring(4, str.length - line.trailing)
-                               else
-                                       text.append str
-                               end
-                       end
-                       text.append "\n"
-                       line = line.next
-               end
-               return text.write_to_string
-       end
  end
  
  # A unit-test to run
@@@ -381,10 -358,10 +358,10 @@@ redef class ModelBuilde
                # usualy, only the original module must be imported in the unit test.
                var o = mmodule
                var g = o.mgroup
 -              if g != null and g.mproject.name == "core" then
 +              if g != null and g.mpackage.name == "core" then
                        # except for a unit test in a module of `core`
                        # in this case, the whole `core` must be imported
 -                      o = get_mmodule_by_name(nmodule, g, g.mproject.name).as(not null)
 +                      o = get_mmodule_by_name(nmodule, g, g.mpackage.name).as(not null)
                end
  
                ts.attr("package", mmodule.full_name)