Patch to cache generated graphs.

[vitalyb]

Hello,

Here's a simple and a bit hacky patch to make graphs cacheable. Two things are done:
1) time intervals are rounded to 300 sec and added http headers to make browsers cache images for 5 minutes;
2) generated graphs saved into memcached (http://www.danga.com/memcached/) cache.

memcached should be installed locally and listen on 127.0.0.1:11211 (you'll have to adjust source otherwise). PHP PECL memcached client should be installed also.

Regards.

[fmangeant]

Hi

the Boost plugin provides PNG caching, you might want to try it.