scripts: recognize '+' also as a unary operator

it fixes the armor sorter in "Blades safe house.esp"

components/compiler/exprparser.cpp

@@ -650,8 +650,13 @@ namespace Compiler
             mOperators.push_back ('m');
             mTokenLoc = loc;
             return true;
+        } else if (code ==Scanner::S_plus && mNextOperand) {
+            // Also unary, but +, just ignore it
+            mTokenLoc = loc;
+            return true;
         }
 
+
         if (code==Scanner::S_open)
         {
             if (mNextOperand)