Document more TODOs as tickets (#1418)

Went through the TODOs, removed a bunch, which are outdated or nothing more than a regular comment, documented a bunch more as actual tickets and made them FIXMEs and unified their structure (`FIXME #TICKETNO DESC` for local tickets, `FIXME: DESC LINK` for external tickets) for easier in-editor support. Further more remove unnecessary remarks and related old code that I noticed in that instance.

substrate/core/basic-authorship/src/basic_authorship.rs

@@ -16,8 +16,8 @@
 
 //! A consensus proposer for "basic" chains which use the primitive inherent-data.
 
-// FIXME: move this into substrate-consensus-common - https://github.com/paritytech/substrate/issues/1021
-
+// FIXME #1021 move this into substrate-consensus-common
+// 
 use std::{sync::Arc, self};
 
 use log::{info, trace};
@@ -197,7 +197,6 @@ impl<Block, C, A> Proposer<Block, C, A>	where
 				let pending_iterator = self.transaction_pool.ready();
 
 				for pending in pending_iterator {
-					// TODO [ToDr] Probably get rid of it, and validate in runtime.
 					let encoded_size = pending.data.encode().len();
 					if pending_size + encoded_size >= MAX_TRANSACTIONS_SIZE { break }