[DesoutterBridge] Add feed item limit
[DesoutterBridge] Add feed item limit

This bridge currently takes a very long time to process
all news items on the page, when in many cases only one
or two had been added since the last check.

This commit adds a new parameter 'limit', which defines
the maximum number of items to add to the feed. This is
an optional paramter that defaults to 3.

ORelio/rss-bridge,sebsauvage/rss-bridge,RSS-Bridge/rss-bridge,kranack/rss-bridge,Riduidel/rss-bridge,RSS-Bridge/rss-bridge,RSS-Bridge/rss-bridge,ORelio/rss-bridge,Riduidel/rss-bridge,kranack/rss-bridge,Riduidel/rss-bridge,kranack/rss-bridge,kranack/rss-bridge,ORelio/rss-bridge,Frenzie/rss-bridge,Frenzie/rss-bridge