Patch for truncated texts

```
Change
$newstr = $retstr[$j].chr(0);
into
$newstr .= $retstr[$j].chr(0);
around line 547 in reader.php.

When the excel's SST record exceeds the BIFF record size (which may happen if
you have more than 8kbyte of unique texts in cells), and a CONTINUE is inserted
in the middle of a string, then only the end of the string is returned for that
cell, the first portion is truncated.
```

Original issue reported on code.google.com by `gergely....@gmail.com` on 30 Nov 2010 at 2:54

Open reader.php around line 547 and inspect how the SST record handles strings split by a CONTINUE record. Reproduce with an Excel file containing more than 8 kB of unique cell text, then verify that the complete string is returned rather than only its final portion.

Written by the indexing model from the issue text.