modulebuilder: module_absolute_path does always its job

This allow to climb-up directories to look for a project

Signed-off-by: Jean Privat <jean@pryen.org>
modulebuilder: remove protection for multiple loading of AST

The protection is now only in the `identify_file` method

Signed-off-by: Jean Privat <jean@pryen.org>
Merge branch 'project_new'