Set mapniks max_size parameter in renderd if configured to  use more than 10 threads.

The default postgresql connection pool size of mapnik is 10, which can get exhausted
on modern multi-core servers.

This sets the max_size parameter to 2 larger than the thread count unless it is
explicitly set in the loaded stylesheet.
Merge branch 'master' of git://github.com/openstreetmap/mod_tile
Fix some minor memory leaks in the testing frame work.

There are still a number of memory leaks in the queueing tests
Free memory when the request queues get closed.
The test suit was not generating unique items to add to the queue

The de-dupplication of the queue then resulted in unexpected behaviour.

This should fix the test suite
Allow timestamp to be specified to render_old as a unix timestamp
Merge pull request #32 from tomhughes/master

Allow render_old to take a unix timestamp
Don't install the unit test program into bin directory
Merge branch 'master' of git://github.com/openstreetmap/mod_tile
Try to improve the update script to be more robust
Make munin graphs support Z19 and Z20
Keep track of how much rendering time is spent in each type of rendering queue
Add a munin graph to display the time spent rendering in each queue
Fix munin graphs
Improve diff-importing and tile expiry script
Make munin graphs support Z19 and Z20
Keep track of how much time is spent with rendering tiles from each queue
Add a munin graph to display the time spent rendering in each queue

This is useful to determine how many resources are used to render missing tiles
and how many to keep things up-to-date
Merge branch 'master' of git://github.com/openstreetmap/mod_tile

Conflicts:
	munin/renderd_queue_time
	replag
Fix #38 clock_gettime needs -lrt on some systems