Improve readability of the search results activity

[CampelloManuel]

Is your feature request related to a problem? Please describe.
The search results activity, accessible from the searchbox on the main activity, is barebones and lacks useful information.

Describe the solution you'd like
Add to the Activity:

• a menu to reorder notes by: due date, last edit date, alphabetic, ...
• a toggle to temporarily hide notes without a due date from the results
• a sorted date view when ordering notes by due date, with "today", "tomorrow", "next week", ...

Idea: move this menu, which is W.I.P.,

from ActivityMain to ActivitySearch, and have the items rerun the query with the selected sorting

the code should update this function in FragmentSearch.java:

	protected String getSortOrder() {
		return Task.Columns.DUE;
	}