Add table pretty printing & alignment

Also dismissed implementing colgroups for now - had it but didn't like the
added complexity for a very questionable benefit - i've actually never used
that feature of org tables...

org/testdata/footnotes.html

@@ -53,13 +53,16 @@ and tables
 <table>
 <tbody>
 <tr>
-<td>1</td><td>a</td>
+<td class="align-right">1</td>
+<td>a</td>
 </tr>
 <tr>
-<td>2</td><td>b</td>
+<td class="align-right">2</td>
+<td>b</td>
 </tr>
 <tr>
-<td>3</td><td>c</td>
+<td class="align-right">3</td>
+<td>c</td>
 </tr>
 </tbody>
 </table>

org/testdata/lists.html

@@ -60,11 +60,17 @@ and another one with a table
 </p>
 <table>
 <thead>
-<th>a</th><th>b</th><th>c</th>
+<tr>
+<th class="align-right">a</th>
+<th class="align-right">b</th>
+<th class="align-right">c</th>
+</tr>
 </thead>
 <tbody>
 <tr>
-<td>1</td><td>2</td><td>3</td>
+<td class="align-right">1</td>
+<td class="align-right">2</td>
+<td class="align-right">3</td>
 </tr>
 </tbody>
 </table>

org/testdata/misc.html

@@ -20,10 +20,12 @@ crazy ain't it?
 <table>
 <tbody>
 <tr>
-<td><strong>foo</strong></td><td>foo</td>
+<td><strong>foo</strong></td>
+<td>foo</td>
 </tr>
 <tr>
-<td><strong>bar</strong></td><td>bar</td>
+<td><strong>bar</strong></td>
+<td>bar</td>
 </tr>
 </tbody>
 </table>

org/testdata/tables.html

@@ -1,11 +1,17 @@
 <figure>
 <table>
 <thead>
-<th>a</th><th>b</th><th>c</th>
+<tr>
+<th class="align-right">a</th>
+<th class="align-right">b</th>
+<th class="align-right">c</th>
+</tr>
 </thead>
 <tbody>
 <tr>
-<td>1</td><td>2</td><td>3</td>
+<td class="align-right">1</td>
+<td class="align-right">2</td>
+<td class="align-right">3</td>
 </tr>
 </tbody>
 </table>
@@ -16,11 +22,17 @@ table with separator before and after header
 <figure>
 <table>
 <thead>
-<th>a</th><th>b</th><th>c</th>
+<tr>
+<th class="align-right">a</th>
+<th class="align-right">b</th>
+<th class="align-right">c</th>
+</tr>
 </thead>
 <tbody>
 <tr>
-<td>1</td><td>2</td><td>3</td>
+<td class="align-right">1</td>
+<td class="align-right">2</td>
+<td class="align-right">3</td>
 </tr>
 </tbody>
 </table>
@@ -31,9 +43,10 @@ table with separator after header
 <figure>
 <table>
 <tbody>
-<tr></tr>
 <tr>
-<td>1</td><td>2</td><td>3</td>
+<td class="align-right">1</td>
+<td class="align-right">2</td>
+<td class="align-right">3</td>
 </tr>
 </tbody>
 </table>
@@ -45,7 +58,9 @@ table without header (but separator before)
 <table>
 <tbody>
 <tr>
-<td>1</td><td>2</td><td>3</td>
+<td class="align-right">1</td>
+<td class="align-right">2</td>
+<td class="align-right">3</td>
 </tr>
 </tbody>
 </table>
@@ -53,3 +68,50 @@ table without header (but separator before)
 table without header
 </figcaption>
 </figure>
+<figure>
+<table>
+<thead>
+<tr>
+<th class="align-left">left aligned</th>
+<th class="align-right">right aligned</th>
+<th class="align-center">center aligned</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td class="align-left">42</td>
+<td class="align-right">42</td>
+<td class="align-center">42</td>
+</tr>
+<tr>
+<td class="align-left">foobar</td>
+<td class="align-right">foobar</td>
+<td class="align-center">foobar</td>
+</tr>
+</tbody>
+</table>
+<figcaption>
+table with aligned columns
+</figcaption>
+</figure>
+<figure>
+<table>
+<thead>
+<tr>
+<th class="align-right">long column a</th>
+<th class="align-right">long column b</th>
+<th class="align-right">long column c</th>
+</tr>
+</thead>
+<tbody>
+<tr>
+<td class="align-right">1</td>
+<td class="align-right">2</td>
+<td class="align-right">3</td>
+</tr>
+</tbody>
+</table>
+<figcaption>
+table with right aligned columns (because numbers)
+</figcaption>
+</figure>

org/testdata/tables.org

@@ -16,3 +16,14 @@
 #+CAPTION: table without header
 | 1 | 2 | 3 |
 
+#+CAPTION: table with aligned columns
+| left aligned | right aligned | center aligned |
+|--------------+---------------+----------------|
+| <l>          |           <r> |       <c>      |
+| 42           |            42 |       42       |
+| foobar       |        foobar |     foobar     |
+
+#+CAPTION: table with right aligned columns (because numbers)
+| long column a | long column b | long column c |
+|---------------+---------------+---------------|
+|             1 |             2 |             3 |