Add support for a loop-command

[whotwagner]

Add support for a loop-command that loops through a block of commands until a condition is met.

[whotwagner]

Add a new type of loop: "until( condition )", where condition has the syntax of the existing class "Conditional". This type of loop, loops until the condition has met.

Also include a "break"-option, that allows to set a condition that can stop any type of loops