Fix bug 834 (various gzip-encoded documents were being truncated),
which I introduced with commit e441361f2c51c0ece87afc3ed68e5c6ea5522f13.
Thanks to Witek for reporting the bug, Kalle for determining the
problematic commit, and Jonas for letting me know about the bug report(!).
Adjust the size of to_read for the initial read instead of setting the init
flag and using that later to check whether to read a smaller amount than
the value in to_read. This also affects the realloc call on the initial
read, which was allocating more memory than necessary (altho this
discrepency would be corrected with the realloc for the next read).
Added document.cache.interval option. When time elapsed since previous access
to the document is less than interval then the document is taken from
the cache. Otherwise the request with filled "If-Modified-Since" and/or
"If-None-Match" header field is sent. By default interval is set to 10 minutes.
This requires the correct time to be set on your machine.
Mostly non-ANSI function declarations, using 0 as NULL and inline
function prototypes. Also removed unused S_HTTP_100 network state
enum type, which text message contained unknown escape sequence: '\?'.
