Upgrade architecture + 5.0 Bot API (#469)

Upgrade architecture + 5.0 Bot API (#469)
* Moved `methods`, `types` and `client` to root package
* Removed update handler from routers to dispatcher
* Reworked events propagation mechanism to handlers
* Reworked inner middlewares logic (very small change)
* Updated to Bot API 5.0
* Initial migration from MkDocs to Sphinx + config for readthedocs

docs2/conf.py

@@ -0,0 +1,59 @@
+import datetime
+
+import aiogram
+
+project = "aiogram"
+author = "aiogram Team"
+copyright = f"{datetime.date.today().year}, {author}"
+release = aiogram.__version__
+api_version = aiogram.__api_version__
+
+templates_path = ["_templates"]
+html_theme = "furo"
+html_logo = "_static/logo.png"
+html_static_path = ["_static"]
+todo_include_todos = True
+pygments_style = "sphinx"
+htmlhelp_basename = project
+html_theme_options = {}
+html_css_files = [
+    "stylesheets/extra.css",
+]
+
+extensions = [
+    "sphinx.ext.todo",
+    "sphinx.ext.viewcode",
+    "sphinx.ext.autodoc",
+    "sphinx.ext.ifconfig",
+    "sphinx.ext.intersphinx",
+    "sphinx-prompt",
+    "sphinx_substitution_extensions",
+    "sphinx_copybutton",
+]
+
+rst_prolog = f"""
+.. |api_version| replace:: {aiogram.__api_version__}
+"""
+
+language = None
+locale_dirs = ["locales"]
+
+exclude_patterns = []
+source_suffix = ".rst"
+master_doc = "index"
+
+latex_documents = [
+    (master_doc, f"{project}.tex", f"{project} Documentation", author, "manual"),
+]
+man_pages = [(master_doc, project, f"{project} Documentation", [author], 1)]
+texinfo_documents = [
+    (
+        master_doc,
+        project,
+        f"{project} Documentation",
+        author,
+        project,
+        "Modern and fully asynchronous framework for Telegram Bot API",
+        "Miscellaneous",
+    ),
+]