Entity_.__ALL_RELATIONS like __ALL_PROPERTIES

Hi,

it would be great if generated entity class had access to array of RelationInfo like it has access to all properties.
Right now eager loading relations requires

1. explicit list of all relations and QueryBuilder.eager
   or
2. hard reflection loop calling getTarget()

Explicit list __ALL_RELATIONS would ease up creating algorithms like eager loading.

What do you think?

首先檢查產生的實體類別如何公開 __ALL_PROPERTIES，然後追蹤 RelationInfo 和 QueryBuilder.eager 在所述 eager-loading 情況下的使用。完成的標準是：產生的實體提供一個類似的 __ALL_RELATIONS 陣列，以支援關聯探索演算法，並為產生的 API 提供涵蓋率。