change int to double for cost related calls

After pulling recent commits and updating link-grammar to 5.1.1 got the followinging error.

```
Exception in thread "main" java.lang.NoSuchMethodError: org.linkgrammar.LGConfig.setMaxCost(I)V
        at relex.RelationExtractor.setMaxCost(RelationExtractor.java:245)
        at relex.RelationExtractor.init(RelationExtractor.java:178)
        at relex.RelationExtractor.setAllowSkippedWords(RelationExtractor.java:250)
        at relex.RelationExtractor.main(RelationExtractor.java:518)
```
this is a fix for the above