Add "function return" and "scoped function return" injections, allow children for return lines

test/tests/return children.ans

@@ -0,0 +1,13 @@
+$ fn
+    :i=0
+    @i
+        ~ i:=5
+        {i}
+
+{fn} = 50
+
+$ g
+    @0
+        @3
+
+{g} = 3

test/tests/return children.lua

@@ -0,0 +1,37 @@
+local _={}
+_[15]={}
+_[14]={}
+_[13]={}
+_[12]={}
+_[11]={}
+_[10]={text=" = 3",tags=_[15]}
+_[9]={text="3",tags=_[14]}
+_[8]={text=" = 50",tags=_[13]}
+_[7]={text="0",tags=_[12]}
+_[6]={text="5",tags=_[11]}
+_[5]={_[9],_[10]}
+_[4]={_[6],_[7],_[8]}
+_[3]={"return"}
+_[2]={"text",_[5]}
+_[1]={"text",_[4]}
+return {_[1],_[2],_[3]}
+--[[
+{ "text", { {
+      tags = {},
+      text = "5"
+    }, {
+      tags = {},
+      text = "0"
+    }, {
+      tags = {},
+      text = " = 50"
+    } } }
+{ "text", { {
+      tags = {},
+      text = "3"
+    }, {
+      tags = {},
+      text = " = 3"
+    } } }
+{ "return" }
+]]--