feat: integrated lesson markup

- added PageExtension plugin to inject custom styles scripts in a page
- removed the livecode integration and enabled PageExtension plugins for
  learn page
- also merged the profile_tab.py with plugins.py
- added a utility to find the macros from given text
- updated the before_save of lesson to find exercises using the macros
  and update the exercises as before

Issue #115

community/www/batch/learn.py

@@ -28,7 +28,7 @@ def get_context(context):
     context.next_url = context.batch.get_learn_url(next_)
     context.prev_url = context.batch.get_learn_url(prev_)
 
-
+    context.page_extensions = get_page_extensions()
 
 def get_chapter_title(course_name, lesson_number):
     if not lesson_number:
@@ -42,4 +42,8 @@ def get_lesson_index(course, batch, user):
     lesson = batch.get_current_lesson(user)
     return lesson and course.get_lesson_index(lesson)
 
-
+def get_page_extensions():
+    default_value = ["community.community.plugins.PageExtension"]
+    classnames = frappe.get_hooks("community_lesson_page_extensions") or default_value
+    extensions = [frappe.get_attr(name)() for name in classnames]
+    return extensions