[doc] Wrapper for elinks binary under dosemu

It filters out startup messages of dosemu.

doc/tools/elinks_dos.py

@@ -0,0 +1,16 @@
+#!/usr/bin/python3
+
+import os
+import sys
+
+if __name__ == '__main__':
+    was_elinks = False
+    d = os.path.dirname(os.getenv('ELINKS_BINARY'))
+    with os.popen('dosemu -dumb -K {0} -E "elinks {1}"'.format(d, sys.argv[1]), 'r') as fi:
+        for line in fi:
+            if not was_elinks:
+                if not line.startswith('ELinks'):
+                   continue
+                was_elinks = True
+            print(line, end='')
+    sys.exit(0)