Quick & dirty interfacePlugin implementation + small import bugfixes

Import bugfixes in settings validator. Hooks must be imported in validatore definition to avoid circular import failure

lodel/plugin/__init__.py

 from .plugins import Plugin, CustomMethod
 from .datasource_plugin import DatasourcePlugin
 from .sessionhandler import SessionHandlerPlugin
+from .interface import InterfacePlugin
 from .extensions import Extension

lodel/plugin/plugins.py

     def __register_types(self):
         plug_type_register(self)
 
-
 def plug_type_register(cls):
     __all_ptypes.append(cls)
     logger.info("New child class registered : %s" % cls.__name__)

lodel/settings/settings.py

 from collections import namedtuple
 
 from lodel import logger
-from lodel.plugin.plugins import Plugin, PluginError
 from lodel.settings.utils import SettingsError, SettingsErrors
 from lodel.settings.validator import SettingValidator, LODEL2_CONF_SPECS, \
     confspec_append
 
     ##@brief This method handles Settings instance bootstraping
     def __bootstrap(self):
+        from lodel.plugin.plugins import Plugin, PluginError
         logger.debug("Settings bootstraping")
         lodel2_specs = LODEL2_CONF_SPECS
         loader = SettingsLoader(self.__conf_dir) 
 
         # Starting the Plugins class
         logger.debug("Starting lodel.plugin.Plugin class")
+        print("DEBUG : plugin list : ", plugin_list)
         Plugin.start(plugin_list)
         # Fetching conf specs from plugins
         specs = [lodel2_specs]

lodel/settings/validator.py

 import inspect
 import copy
 
-from lodel.plugin.hooks import LodelHook
 
 ## @package lodel.settings.validator Lodel2 settings validators/cast module
 #
         raise SettingsValidationError(msg % value)
 
 def emfield_val(value):
+    from lodel.plugin.hooks import LodelHook
     spl = value.split('.')
     if len(spl) != 2:
         msg = "Expected a value in the form CLASSNAME.FIELDNAME but got : %s"
     return value
 
 def plugin_val(value):
+    from lodel.plugin.hooks import LodelHook
     spl = value.split('.')
     if len(spl) != 2:
         msg = "Expected a value in the form PLUGIN.TYPE but got : %s"
     'lodel2': {
         'debug': (  True,
                     SettingValidator('bool')),
-        'plugins_path': (   None,
-                            SettingValidator('list')),
-        'plugins': (    "",
-                        SettingValidator('list')),
         'sitename': (   'noname',
                         SettingValidator('strip')),
         'runtest': (    False,

tests/tests_conf.d/lodel2.ini

 [lodel2]
 debug = False
 sitename = noname
-plugins_path = /foo/plugins
-plugins = dummy, dummy_datasource
 runtest=True
 extensions = dummy
 datasource_connectors = dummy_datasource
-session_handler = filesystem_session
+session_handler = ram_session
 
 [lodel2.logging.stderr]
 level = Error