Move almost all addon files into a single subfolder. Only installation files are in the main folder.

Signed-off-by: enyst <engel.nyst@gmail.com>
Move install.xml in the main addon folder.

Signed-off-by: enyst <engel.nyst@gmail.com>
Update installation.

Signed-off-by: enyst <engel.nyst@gmail.com>
Move upgrade and hooks installation to main folder.

Signed-off-by: enyst <engel.nyst@gmail.com>