Fix ZERO_BALANCE_VALIDATOR_TTL and move get_domain

specs/core/0_beacon-chain.md

@@ -65,6 +65,7 @@
             - [`bytes1`, `bytes2`, ...](#bytes1-bytes2-)
             - [`get_effective_balance`](#get_effective_balance)
             - [`get_new_validator_registry_delta_chain_tip`](#get_new_validator_registry_delta_chain_tip)
+            - [`get_domain`](#get_domain)
             - [`integer_squareroot`](#integer_squareroot)
         - [On startup](#on-startup)
         - [Routine for activating a validator](#routine-for-activating-a-validator)
@@ -172,7 +173,7 @@ Unless otherwise indicated, code appearing in `this style` is to be interpreted
 | `POW_RECEIPT_ROOT_VOTING_PERIOD` | `2**10` (= 1,024) | slots | ~1.7 hours |
 | `SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD` | `2**17` (= 131,072) | slots | ~9 days |
 | `COLLECTIVE_PENALTY_CALCULATION_PERIOD` | `2**20` (= 1,048,576) | slots | ~73 days |
-| `ZERO_BALANCE_VALIDATOR_TTL` | `2**22` (= 16,777,216) | slots | ~290 days |
+| `ZERO_BALANCE_VALIDATOR_TTL` | `2**22` (= 4,194,304) | slots | ~291 days |
 
 ### Reward and penalty quotients
 
@@ -922,6 +923,18 @@ def get_new_validator_registry_delta_chain_tip(current_validator_registry_delta_
     )
 ```
 
+#### `get_domain`
+
+```python
+def get_domain(fork_data: ForkData,
+               slot: int,
+               domain_type: int) -> int:
+    return get_fork_version(
+        fork_data,
+        slot
+    ) * 2**32 + domain_type
+```
+
 #### `integer_squareroot`
 
 ```python
@@ -1038,14 +1051,6 @@ def get_fork_version(fork_data: ForkData,
     else:
         return fork_data.post_fork_version
 
-def get_domain(fork_data: ForkData,
-               slot: int,
-               domain_type: int) -> int:
-    return get_fork_version(
-        fork_data,
-        slot
-    ) * 2**32 + domain_type
-
 def get_new_validators(validators: List[ValidatorRecord],
                        fork_data: ForkData,
                        pubkey: int,