Constraints on variable names

[romaintailhurat]

We define some good practices and constraints for Pogues variables naming here.

It would be better to implement them directly in Pogues.

[romaintailhurat]

With rule being [A-Z0-9_]*, we can have:

let rule = /[A-Z0-9_]*/
let badName = "bad-Var_Name" 
let ruleCheck = rule.exec(badName)
let checkOK = check[0] != badName ? false : true