RFR: Grand heuristics and tests rehash

[Roman Kennke]

> On 09/06/2018 09:37 PM, Aleksey Shipilev wrote:
>> Therefore, I vote for removing all partial heuristics and the associated matrix code. Removing that
>> code simplifies our development, testing, and backporting significantly. There is even less need to
>> drag this thing upstream. If we ever need matrix stuff back, we can revert it from the Mercurial
>> history.
> 
> My dirty removal patch recovers >2 KLOC:
>    49 files changed, 85 insertions(+), 2097 deletions(-)
> 
> It would probably remove more once I search for unused methods.
> 
> -Aleksey
> 

Great! I'm also for removing it. We can revive the matrix stuff if we
ever need it back.

Roman