Poll choices with less than 1% of votes are displayed as having 0 votes

I'm running a Borda ranking poll with about 50 choices. Some choices in the poll have votes, but less than 1% of the total vote points. These choices incorrectly show up as having 0 votes. This is a critical credibility issue — users are casting votes, but the system makes it appear as though their votes did not count.

Currently, advpoll is doing 2 things that are causing misleading results for my poll:

1. truncating the floating-point percentage value (causing the percentage bars to incorrectly display 0% for choices that have between 0% and 1% of votes)
2. grouping choices together using the above truncated floating-point percentage value (causing choices with greater than 0 points to incorrectly display as having 0 points)

I've attached a patch which:

1. modifies advpoll_calculate_percentage() to return floating-point percentage values (without truncating)
2. truncates percentages when they're displayed as text (but not when they're used to affect the width of the percentage bar)
3. modifies advpoll_display_borda_results() grouping algorithm, to group choices by the number of points they have, instead of grouping by percentage