Refactor the model accesors

Refactor the accesors to behave like methods instead of properties.
This means all accesors will be prepended with the string
"get_" and will include a set of parenthesis.

Improve the ModeAttribute class to use the method's
short_description. This commit also adds support for a
new method .help_text attribute has been added.

Move accessors to their own module, named "methods.py".

Remove the PropertyHelper class as the accessors no longer
need it.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/document_parsing/utils.py

@@ -5,20 +5,24 @@ from django.utils.encoding import force_text
 from django.utils.html import conditional_escape
 
 
-def get_document_content(document):
+def get_document_content_iterator(document):
+    latest_version = document.latest_version
+
+    if latest_version:
+        return get_document_version_content_iterator(
+            document_version=latest_version
+        )
+
+
+def get_document_version_content_iterator(document_version):
     DocumentPageContent = apps.get_model(
         app_label='document_parsing', model_name='DocumentPageContent'
     )
 
-    for page in document.pages.all():
+    for page in document_version.pages.all():
         try:
             page_content = page.content.content
         except DocumentPageContent.DoesNotExist:
             return
         else:
             yield conditional_escape(force_text(page_content))
-
-
-@property
-def document_property_content(self):
-    return ' '.join(get_document_content(self))