Make MaEditor independent from MaEditorWgt

MaEditor and MaEditorWgt are closely connected now. For that reason, they look like one large class, which has been randomly spitted. There is a point to re-organize them to make the separation more logical. For example: MaEditorWgt contains a lot of components like MaEditorSequenceArea, MaEditorOverviewArea and so on. If these components are required in MaEditor (e.g. MaEditorSequenceArea is definitely required, because there is a "get" function called) there is a point to move them there, because MaEditorWgt doesn't need them by it's own, it just need widgets, which these components contain. 

Don't forget to make the same thing for MCA and MSA branches.