Calculate all cache sizes from single memory cache size option and sanity check
have a single global struct to hold all parameters instead of several individual variables
svn path=/trunk/netsurf/; revision=12784
Remaining work:
1) Clone content_html_data
2) Cloning content_css_data requires the charset of the old content
3) Calling hlcache_handle_abort() before a content has been created must clean up the retrieval context.
svn path=/trunk/netsurf/; revision=10236
