Per the request of spaceman_atlas, the No Release mod is rewritten to
avoid modifications to DrawableHoldNoteTail. The approach is based
on that of the Strict Tracking mod for the osu!(standard) ruleset,
injecting the mod behavior by replacing the normal hold note with
the mod's variant. The variant inherits most bevaior from the normal
hold note, but when creating nested hitobjects, it creates its own
hold note tail variant instead, which in turn is used to instantiate
the mod's variant of DrawableHoldNoteTail with a new behavior.
The time a judgement is awarded is changed from the end of its
Perfect window to the time of the tail itself.
This commit adds a new osu!mania mod No Release that relaxes tail
judgements. The current implementation automatically awards Perfect
(or Meh if the hold note is broken midway) for a hold note tail at
the end of its Perfect window, as long as it is held by then.
Tests are pending for the next commit.
