Export Function does not work when Macro is not enabled

At the moment Macro is not a dependency of Patterns.

However, some Patterns components require macro_get_macro in order to parse the database configuration. If that is missing a critical error is raised.

The bug is critical because, if the cache is not refreshed, some Drupal functions (like installing new modules) are inhibited by the same error.

Solutions are:

- Simple: add Macro as a dependency of Patterns
- Medium: add Macro as a dependency of Patterns_Components (maybe it is not a good idea, because the Patterns api requires Macro anyway).
- Complex: refactor the codebase, and isolate the Patterns code that require Macro as a dependency.