Added support for parsing ASCII (alt style) tables with multi-line values

Parses tables were cell content may be distributed over multiple lines, e.g.:

```
+--------------------------------------+--------------------------------------+
| Acronym                              | Description                          |
+--------------------------------------+--------------------------------------+
| HTTPS                                | Secure Hypertext Transfer Protocol   |
+--------------------------------------+--------------------------------------+
| IRI                                  | Internationalized Resource           |
|                                      | Identifier                           |
+--------------------------------------+--------------------------------------+
```

or  like:

```
+--------------------------------------+--------------------------------------+
| Prefix                               | Namespace                            |
+--------------------------------------+--------------------------------------+
| rdf                                  | [http://www.w3.org/1999/02/22-rdf-sy |
|                                      | ntax-ns\#](http://www.google.com/url |
|                                      | ?q=http%3A%2F%2Fwww.w3.org%2F1999%2F |
|                                      | 02%2F22-rdf-syntax-ns%23&sa=D&sntz=1 |
|                                      | &usg=AFQjCNHlHXopcxjLZnliePrsUehDZFF |
|                                      | erA)                                 |
+--------------------------------------+--------------------------------------+
| rdfs                                 | [http://www.w3.org/2000/01/rdf-schem |
|                                      | a\#](http://www.google.com/url?q=htt |
|                                      | p%3A%2F%2Fwww.w3.org%2F2000%2F01%2Fr |
|                                      | df-schema%23&sa=D&sntz=1&usg=AFQjCNE |
|                                      | 9em93Bt6zPm9Mlq5PMSo1mS38KQ)         |
+--------------------------------------+--------------------------------------+
```