Problems with Generated `define.go`

[DavePearce]

There are a number of issues with the generated define.go file. Here is a rough list, with minimal examples to follow:

• Formatting. The generated define.go does not pass gofmt (see #191)

• Unused Variables. The generated define.go declares variables even when they are not used. (see #179)

• More Unused Variables. The generated define.go still includes variables which are not used. (see #209)

• Undefined Variables. The generated define.go sometimes refers to variables which have not been declared (see #177)

• Duplicate Variables. The generated define.go declares variables more than once (see #178).

• Mul Arguments. The generated define.go has Mul expressions with more than two arguments (see #203).

@gusiri FYI.