- hooked ssl and ssl_letsencrypt checkboxes

- added limit for letsencrypt and directive snippets selector to client limits
- hide ssl tab if letsencrypt is selected

- removed most static content from scrigo

- Directive snippets can now be made available to clients; clients can select an available directive snippet for a website - the appropriate snippet will then be written to the vhost configuration file. This is useful for example on nginx where clients have no access to the Options tab of a website.

(nginx still missing)

Fixed: password match function blocked tabs incorrectly
Fixed: set focus on username input field threw an error if this field did not exist on a page

Moved old default theme to themes/default-304

Added: Form fields are disabled if a client is not allowed to edit a domains main settings

Fixed (partly) FS#2310 - Template switch not working in mailuser module, for dashlets and the login page

- Fastcgi: delete .php-fcgi-starter directory if another PHP mode is used.