first verison of layer name builder

1.5.3

- feat: quick-prefix for layer using pref separator
  - list editable in addon pref
  - add interface button above layers
- code: added environnement variable for prefix and separator:
  - `PREFIXES` : list of prefix (comma separated uppercase letters between 1 and 6 character, ex: 'AN,SP,L')
  - `SEPARATOR` : Separator character to determine prefixes, default is '_' (should not be a special regex character)
- UI: add addon prefs namespace ui-box in project settings

properties.py

@@ -127,6 +127,10 @@ class GP_PG_ToolsSettings(bpy.types.PropertyGroup):
             ('JITTER', 'Jitter', '', 'KEYTYPE_JITTER_VEC', 5),
             ))
 
+    layer_name : StringProperty(
+        name="Layer Name",
+        description="The layer name, should describe the content of the layer",
+        default="")# update=None, get=None, set=None
     """ 
     reconnect_parent = bpy.props.PointerProperty(type =bpy.types.Object,poll=poll_armature)
     render_settings = bpy.props.BoolProperty(default = False)