Fix mistype

... in commit 2fe749bb23dd7873cd85017077e8995703a61f36
Merge branch 'dev-noround'
Correct ASS focal length to width*4/3
Manual BT.709 conversion
Revert "Correct ASS focal length to width*4/3"

This reverts commit 4fa2a01e1e2dea830d18fffd80f2fc3702e546ff.
Merge branch 'dev-bt709' into py2

Conflicts:
	danmaku2ass.py
Fix mistype

... in commit a145947772363f95948f84eac9b4f39f5f1429c9