server: refactor + add type hinting

- Added type hinting (for now, 3.5-compatible)
- Split `db` namespace into `db` module and `model` namespace
- Changed elastic search to be created lazily for each operation
- Changed to class based approach in entity serialization to allow
  stronger typing
- Removed `required` argument from `context.get_*` family of functions;
  now it's implied if `default` argument is omitted
- Changed `unalias_dict` implementation to use less magic inputs

1 files changed, 2 insertions, 2 deletions

diff --git a/server/szurubooru/migrations/env.py b/server/szurubooru/migrations/env.py
index 1359ab8..a4257d4 100644
--- a/server/szurubooru/migrations/env.py
+++ b/server/szurubooru/migrations/env.py
@@ -2,7 +2,7 @@ import os
 import sys
 
 import alembic
-import sqlalchemy
+import sqlalchemy as sa
 import logging.config
 
 # make szurubooru module importable
@@ -48,7 +48,7 @@ def run_migrations_online():
     In this scenario we need to create an Engine
     and associate a connection with the context.
     '''
-    connectable = sqlalchemy.engine_from_config(
+    connectable = sa.engine_from_config(
         alembic_config.get_section(alembic_config.config_ini_section),
         prefix='sqlalchemy.',
         poolclass=sqlalchemy.pool.NullPool)