Use calloc() in TranspositionTable::set_size()

Function calloc() already initializes memory to
zero, so avoid calling clear() afterwards.

Also some renaming while there (inspired by DiscoCheck).

No functional change.
Extend fail low singular moves on the next iteration
Always extend SEs on the next iteration
Reorder conditions according to their frequency

This should minimize useless tests.

No functional change.
Simplify search results update

Also some rename while there.

No functional change.
Fix a stale comment

No functional change.
Cleaned up version
Merge branch 'master' of https://github.com/mcostalba/Stockfish into SEHash

Conflicts:
	src/search.cpp
	src/tt.cpp
	src/tt.h
Without extend
Store for future
Entering a pawn endgame is no more dangerous

A simplification of the 'dangerous' definition.

Seems neutral at reverse test at long TC

master vs patch
LLR: -2.96 (-2.94,2.94)
Total: 16974 W: 3122 L: 3139 D: 10713

bench: 4689029
Merge branch 'master' of https://github.com/mcostalba/Stockfish into SEHash