scope: create two escapemaks in loops

Signed-off-by: Jean Privat <jean@pryen.org>
astbuilder: can make loops and breaks

Signed-off-by: Jean Privat <jean@pryen.org>
transform: transforms `while` and `for`

Signed-off-by: Jean Privat <jean@pryen.org>
transform: shortcut range

Signed-off-by: Jean Privat <jean@pryen.org>
transform: move up shortcut-range from abstract_compiler to transform

Signed-off-by: Jean Privat <jean@pryen.org>