Extract classes

Extract files to fix composer warning.

Here is the warning message given from composer.
```sh
Warning: Ambiguous class resolution, "nfephpException" was found in both
"/Users/antonio/Projects/kanui/store/vendor/kanui/nfephp/libs/CTeNFePHP.class.php" and
"/Users/antonio/Projects/kanui/store/vendor/kanui/nfephp/libs/ToolsNFePHP.class.php",
the first will be used.
```