#11 Improve const-correctness

[Markus Elfring]

Would you like to apply the advices from the article "http://en.wikipedia.org/wiki/Const-correctness" to more places in your sources?
I suggest to add the key word "const" to the type specifiers for parameters like the following.
http://w3m.cvs.sourceforge.net/w3m/w3m/proto.h?revision=1.101&view=markup
hostname, remoteport_name, remoteport_num (function "openSocket")
filename (function "guessContentType")
check_no_proxy (function "domain")
name (function "get_param_option")
myExec (function "command")