First SQL support

Add the SQL support:
SQL driver loader
MySQLi driver for MySQL
config.php updated with new supported settings
More drivers coming! In the future, the framework should support the old
MySQL interface and MSSQL.

Kernel bootloader:
Start the SQL driver loader

"Protected" Kernel module:
Updated variable clearing: Now, if the content is empty, the variable is
removed from memory (unset)

.gitignore:
Update to exclude line counting script

NOTE:
The provided MySQLi driver is in BETA. It does not support all of the
SQL function. The workaround is to use the SQL_query function.
No doc for SQL usage available for now but is currently being written
(not top priority)