Fix: integer argument expected, got float

It appears that Biligrab cannot deal with it with a ```pass``` in its function.

So here I come:

```ERROR:root:'tuple' object has no attribute 'startswith'
INFO: Converting danmaku to ASS file with danmaku2ass(py2)...
INFO: Trying to get resolution...
INFO: Resolution is 1280x720
ERROR: Danmaku2ASS failed: integer argument expected, got float
       Head to https://github.com/m13253/danmaku2ass/issues to complain about this.
Traceback (most recent call last):
  File "b2.py", line 573, in convert_ass_py2
    font_size = int(math.ceil(resolution[1] / 21.6)), text_opacity= 1, comment_duration=8.0)
  File "/Users/Beining/Movies/danmaku2ass2.py", line 781, in Danmaku2ASS
    ProcessComments(comments, fo, stage_width, stage_height, reserve_blank, font_face, font_size, text_opacity, comment_duration, is_reduce_comments, progress_callback)
  File "/Users/Beining/Movies/danmaku2ass2.py", line 583, in ProcessComments
    row = FindAlternativeRow(rows, i, height, bottomReserved)
  File "/Users/Beining/Movies/danmaku2ass2.py", line 630, in FindAlternativeRow
    for row in xrange(height-bottomReserved-math.ceil(c[7])):
TypeError: integer argument expected, got float```

Noticeable, on L640:
```        for i in xrange(row, row+int(math.ceil(c[7]))):```

There already existed a ```int()```.

This fix will be pushed in the latest version of Biligrab. Works well for me.