add getters from() and to() to ranges (start and end)
add getter increment() to ranges
add some spaces
taking into account @jponge comments
space, the final frontier
Merge pull request #55 from k33g/range-plus

Range getter methods: to(), from() and increment()
Update predefined-functions.asciidoc
Yet another closures capture fix

The previous implementation had two major flaws.

1. var references in a closure would all be turned into let. Only references captured shall be
transformed.

2. Assignment checkings did not propagate to child blocks, allowing code such as:

    let a = 1
    if true {
      a = 2
    }

Along the way I also added a trace of compilation problems in the tests suite Golo code loader.