Portability: Updated to make main re-entrant()

- New INSTALL instructions to emscripten, and AUTHORS for contribution.

src/commands/CmdExport.cpp

@@ -30,8 +30,6 @@
 #include <Filter.h>
 #include <main.h>
 
-extern Context context;
-
 ////////////////////////////////////////////////////////////////////////////////
 CmdExport::CmdExport ()
 {
@@ -68,11 +66,11 @@ int CmdExport::execute (std::string& output)
   // Obey 'limit:N'.
   int rows = 0;
   int lines = 0;
-  context.getLimits (rows, lines);
+  Context::getContext ().getLimits (rows, lines);
   int limit = (rows > lines ? rows : lines);
 
   // Is output contained within a JSON array?
-  bool json_array = context.config.getBoolean ("json.array");
+  bool json_array = Context::getContext ().config.getBoolean ("json.array");
 
   // Compose output.
   if (json_array)
@@ -101,7 +99,7 @@ int CmdExport::execute (std::string& output)
   if (json_array)
     output += "]\n";
 
-  context.time_render_us += timer.total_us ();
+  Context::getContext ().time_render_us += timer.total_us ();
   return rc;
 }