Moderation queue improvement: redirection

[dregad]

Original request from mantisbt/mantisbt#2160 (comment):

• Approving an item should not redirect to it, this is annoying for the moderator. The plugin must stay in the moderation queue, and add a button or link for the moderator to click if they do want to view the item.

Discussion:

@vboctor: We don't store the created issue or issue note in the moderation tables

If feasible technically (did not check if it is the case), maybe it would be a nice usability improvement (not required for initial release though).