check if all .cfg.php files are writable at once before starting installing

[anwfr]

(a.l.e)
when installing anwiki, the following files must be writable:

_override/global/global/global.cfg.php
_override/drivers/storagedrivers/storagedriver_mysql/storagedriver_mysql.cfg.php
_override/drivers/usersdrivers/usersdriver_mysql/usersdriver_mysql.cfg.php
_override/drivers/sessionsdrivers/sessionsdriver_mysql/sessionsdriver_mysql.cfg.php
_override/drivers/aclsdrivers/aclsdriver_configrules/aclsdriver_configrules.cfg.php

if would be nice if the files would not be checked one after the other but all together (or in groups).

currently, the install process gets blocked 5 times.

not a tragedy... but still a bit annoying...

[anwfr]

Agree... a new method will be added to driver interface, in order getting each driver to declare required file permissions and/or additional system requirements.