Zena zena

Much better test condition parser in [if] and such places. Added 'join_if' option to [each]. This commit removes compatibility with traditional comparaison operators (<,>,=,...) in favor of 'lt', 'gt'. Having two ways to say the same thing (one possibly breaking zafu rendering in html editors) was a bad thing which needs cleanup before 1.0. There is also a change in the way attributes are handled. We no longer insert 'to_s' every time an attribute is compared. So empty is now detected with <r:if test='custom_a eq nil'/> (integer value) or <r:if test='d_foo eq ""'/> (string). http://github.com/zena/zena/comm...