Make possible to select datasource

There are issues → about the memory usage and about performance → , or about the size of the database table → .

In 🐛 Allowed memory size Closed: outdated @AohRveTPV had an idea about hacking the import.inc to change the data source. And I have to realized all of the previously mentioned problems have the same root cause: Browscap module wants to parse a too big datasource.

I checked my projects where I use Browscap and I found that those projects does not need every informations the normal sized browscap.ini provides. The lite version of browscap.ini would be enough for them.

So the attached patch adds a new field to the admin form where the user/administrator can select the data source. They can select the Lite, Normal or Full datasource. The patch also modifies the _browscap_import() so it can use the selected datasource.