Strings: remove typed declarations

[djbe]

Refers: SwiftGen/SwiftGen#231

The context variable typednames which is an array containing typed declarations like "let p0: String","let p1: Int". Had to add that because there was no easy way to construct that directly in the template from the other variables. Using the MapNode, we should be able to construct those from the types and names context.

Same for declarations which contains let p0, let p1, etc… that we can probably construct from the names with is an array of p0, p1 and a MapNode

Even the names variable in the String context might now maybe be constructible in the template itself using a MapNode and the forloop.index or something

count isn't needed either...