do not disable renderer just because it segfaults occasionally;
some mapnik versions tend to segfault when asked to render bitmaps
near the date line.


git-svn-id: http://svn.openstreetmap.org/applications/utils/tirex@29569 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4
when iterating over a range with multiple styles, make the innermost loop go over the styles
as it is likely that similar database requests will result and caching will be used better.


git-svn-id: http://svn.openstreetmap.org/applications/utils/tirex@29570 b9d5c4c9-76e1-0310-9c85-f3177eceb1e4