core (plugins): added missing contants + use of new constants in PLUGIN_INFO

src/core/constants.py

@@ -176,9 +176,17 @@ class Const(object):
     # PLUGIN_INFO keys
     # XXX: we use PI instead of PLUG_INFO which would normally be used
     #      to make the header more readable
+    PI_NAME = u'name'
     PI_IMPORT_NAME = u'import_name'
+    PI_MAIN = u'main'
+    PI_HANDLER = u'handler'
+    PI_TYPE = u'type'
+    PI_MODES = u'modes'
+    PI_PROTOCOLS = u'protocols'
     PI_DEPENDENCIES = u'dependencies'
     PI_RECOMMENDATIONS = u'recommendations'
+    PI_DESCRIPTION = u'description'
+    PI_USAGE = u'usage'
 
     # Types
     PLUG_TYPE_XEP = "XEP"