yearmonths plugin: Use the current (or default) flavor for permalinks
yearmonths plugin: Use the current (or default) flavor for permalinks

Rather than hardcoding .html

Signed-off-by: Sebastian Spaeth <98dcb2717ddae152d5b359c6ea97e4fe34a29d4c@SSpaeth.de>

daitangio/pyblosxom,willkg/douglas,daitangio/pyblosxom,willkg/douglas