Merge branch 'Mario/electro_combo_over_time' into 'master'

Add an option for Electro combos to deal damage over time

Minor tweak to the combo particle effect to give it a more pronounced border

See merge request xonotic/xonotic-data.pk3dir!1067

diff --cc bal-wep-mario.cfg
Simple merge

diff --cc bal-wep-nexuiz25.cfg
Simple merge

diff --cc bal-wep-samual.cfg
Simple merge

diff --cc bal-wep-xdf.cfg
Simple merge

diff --cc bal-wep-xonotic.cfg
Simple merge