mint UD instead of deposit + disable burn

closes #279 (closed)
closes #284 (closed)
closes #231 (closed) (did not want to do a separate MR for this one)

docs/api/runtime-calls.md

@@ -12,7 +12,7 @@ Calls are categorized according to the dispatch origin they require:
 
 We only document user calls below.
 
-There are **64** user calls from **17** pallets.
+There are **63** user calls from **17** pallets.
 
 ## Account - 1
 
@@ -105,28 +105,6 @@ The dispatch origin of this call must be Signed.
   transfer everything except at least the existential deposit, which will guarantee to
   keep the sender account alive (true).
 
-### burn - 10
-
-<details><summary><code>burn(value, keep_alive)</code></summary>
-
-No weight available.
-
-```rust
-value: T::Balance
-keep_alive: bool
-```
-</details>
-
-
-
-Burn the specified liquid free balance from the origin account.
-
-If the origin's account ends up below the existential deposit as a result
-of the burn and `keep_alive` is false, the account will be reaped.
-
-Unlike sending funds to a _burn_ address, which merely makes the funds inaccessible,
-this `burn` operation will reduce total issuance by the amount _burned_.
-
 ## OneshotAccount - 7
 
 ### create_oneshot_account - 0