Got rid of proxy methods in MatrixBot, v0.6.0

- Updated README.md
- Updated examples
- `MatrixBot` does not redefine methods from classes it is composed of anymore

examples/echo_bot.py

@@ -15,7 +15,7 @@ from _environment import check_environment
 
 async def on_text_message(ctx: EventContext) -> None:
     """This callback is called when a text message arrives."""
-    await ctx.bot.send_text(ctx.room, ctx[CTX_BODY])
+    await ctx.bot.send.text(ctx.room, ctx[CTX_BODY])
 
 async def main() -> None:
     """Application entry point"""