bsip35: handle settling after globally settled

bsip-0035.md

@@ -204,6 +204,8 @@ may be paying something for nothing in current system):
 * when matching a limit order with a call order, process the limit order
 * when matching a force settle order with a call order, process the settle order
 * when globally settling, process the settlement fund
+* when force settling after an asset has been globally settled, paying the force
+  settle order from global settlement fund, process the settle order
 
 ## The Improved Solution (This BSIP)
 
@@ -236,6 +238,10 @@ The detailed rules proposes in this BSIP (new rules highlighted):
     collateral amount
     * **when the asset is not a prediction market, if a call order would pay
    nothing, let it pay 1 Satoshi (round up).**
+  * when paying a settle order from global settlement fund, in favor of global
+    settlement fund, round down receiving collateral amount
+    * **when the asset is not a prediction market, if the settle order would
+   receive nothing, raise an exception (aka let the operation fail).**
 
 Take the example mentioned in the 4th comment of [bitshares-core
 issue #132](https://github.com/bitshares/bitshares-core/issues/132):
@@ -310,6 +316,12 @@ need to check the label, if found it's completed, process next asset.
 In `global_settle_asset(...)` function of `database` class, check each `pays`,
 once it's zero, and the asset is not a prediction market, let it be `1`.
 
+## When Paying A Settle Order From Global Settlement Fund
+
+In `do_apply(...)` function of `asset_settle_evaluator` class,
+after calculated `settled_amount`, check if it is zero. If the answer is `true`,
+and the asset is not a prediction maket, throw a `fc::exception`.
+
 # Discussion
 
 There is an argument suggests when matching call orders, we should always