Fix starting field number

This commit makes starts the counter as `IntSingle 0` instead of `IntSingle 1`. This is needed because `newFormIdent` yield the incremented state value. Meaning: right now, all of my forms start at f2 instead of f1. This commit will make them start at f1 like I would expect them to.
Merge pull request #731 from andrewthad/master

Fix starting field number