Brought back default effect fading: (adding a wipe effect makes it
wipe by default for the length of the strip)
First round in upgrading IPOs from older versions. (works for non-IPO
case now and sets at least the new "default effect fade"-flag)
Still non-working for old IPOs, since Sequence-Strips aren't real IDs!
And: non-frame-lock case should stretch the FCurve to the right length!
a22cfe99db