#6 parameter to turn off proxy's cache

[Santiago Garcia Mantinan]

I think it would be good to have an option to force the Pragma: nocache
option to be sent so that transparent proxies or normal ones don't try
to use their cache and fetch a new version of the document.

I know this can be trigered via reloading with R, but if you use the command
line option -dump you cannot do it.

Thanks for this great browser, regards!