HTML export: Fix alignment bug

HTML export: Fix alignment bug

Patch by Stephen Peters.

Stephen writes:

> When creating a table, I was noticing that the
> <colgroup><col>... provides useful alignment information based on
> whether or not the column has numbers in it.  I think, however, that
> there is a mistake in this routine.  Take, for example, the following
> table:
>
> |  Id | Task         | Developer | Estimate | Spent | Remaining | Comp.% | Updated         |
> |-----+--------------+-----------+----------+-------+-----------+--------+-----------------|
> |   1 | Task One     | SLP       |        1 |     0 |         1 |      0 | SLP, 2010-04-27 |
> |   2 | Task Two     | SLP       |        1 |     0 |         1 |      0 | SLP, 2010-04-27 |
> |   3 | Task Three   | SLP       |        2 |     0 |         2 |      0 | SLP, 2010-04-27 |
> |   4 | Task Four    | SLP       |        2 |     0 |         2 |      0 | SLP, 2010-04-27 |
> |   5 | Task Five    | SLP       |      .25 |     0 |      0.25 |      0 | SLP, 2010-04-27 |
> | 5.1 | Another Task | XML team  |        0 |     1 |         0 |      0 | SLP, 2010-04-27 |
> |   6 | Task Six     | SLP       |      .25 |     0 |      0.25 |      0 | SLP, 2010-04-27 |
> | 6.1 | More Tasks   | DB team   |        3 |     0 |         3 |      0 | SLP, 2010-04-27 |
> |   7 | Task Seven   | SLP       |        3 |     0 |         3 |      0 | SLP, 2010-04-27 |
>
> When the colgroup list is created for this table, it reads:
>
> <colgroup><col align="right" /><col align="left" /><col align="left" /><col align="right" /><col align="right" /><col align="left" /><col align="left" /><col align="left" />
> </colgroup>
>
> Note that the first columns are correct, but the last few are not.  It
> should read right, left, left, right, right, right, right, left.
>
> I believe that this is due to the (< i nline) comparison within
> org-format-org-table-html, which is nonsensical because it's trying to
> compare a column number with a number of rows.  I've attached a patch
> for the problem.