Major error in isConflicted method in Section entity

[Kai15116]

Major problem was found in isConflicted method in Section entity, where isConflicted returns false when block of one section contains the block of another section.

For example, if one section has block between 12:00 and 13:30 and another section contains block between 11:00 and 14:00 in the same day, isConflicted returns false even though it should return true.

This issue is responsible for fixing this problem.