How to migrate your applications from version 0.5.2 to 0.6

(:title How to migrate your applications from version 0.5.2 to 0.6:)

In order to migrate your applications to Porcupine 0.6 you need to apply the following changes:

# @@`HttpContext.current()@@ is deprecated. Use @@from porcupine import context@@ instead.
# Remove all @@__slots__@@ class attributes from all of your schema related classes.
# @@porcupine.security.objectAccess.getAccess@@ is deprecated. Use @@porcupine.utils.permsresolver.get_access@@ instead.
# You no longer have to pass as an argument the transaction handle to transactional API calls. For instance, @@self.delete(txn)@@ should be replaced with @@self.delete()@@.
# `QuiX boxes are no longer automatically redrawn when removing a child widget. The developer should take care of this.
# @@`QuiX.getOS@@ is deprecated. Use @@`QuiX.utils.`BrowserInfo.OS@@ instead.
# Most of the camelCase API calls are deprecated due to PEP 8 alignment. Check the server's log for deprecated calls and change the code accordingly.