Adds memory search comparisons for Increased, Increased By, Decreased, Decreased By, Changed, Not Changed, Changed By.
For arrays, adds not equals, changed, not changed for filter searches.
Now only shows the comparison types that are currently valid for the given search type and if there's prior search results.
Also refactors to allow holding the prior set of search results rather than just the addresses, needed for these search comparisons to work.
Also adds a ui label to show that the debugger is searching after clicking the search button which then gets replaced with the results count when the search completes.
Moves the Memory Search fucntionality to it's own widget so as to not pollute the CpuWidget with search related functionality, especially as it is intended to grow in scope. CpuWidget is fairly general and as such everything tends to get tossed together which makes it harder to navigate/understand/maintain.
