#3 Improve const correctness

[Markus Elfring]

Would you like to apply the advices from the article
"http://en.wikipedia.org/wiki/Const_correctness" to
your sources?
I suggest to add the key word "const" to the type
specifiers for parameters like "acl" in the function
"add_acl".
http://cvs.sourceforge.net/viewcvs.py/transproxy/transproxy/acl.h?rev=1.1.1.1&view=markup