minor tuning + intel compiler builds

* About ~16% overall perf gain with intel compiler:
- get rid of asserts (esp the one called from bitScan function). For
some wired reason MSVC compiler generates significantly faster code when
that assert is present! No such issue with intel compiler.
- get rid of __forceinline. With normal 'inline' or without any keword,
intel compiler is able to produce significantly better code.
- use plain magics (quite a bit faster with intel compiler)
- minor adjustment in some parameters
* > 1 billion moves per second on 4790k (stock speed) for pos2 from
chess programming wiki:
Perft 7: 374190009323,   Time taken: 361.762 seconds, nps: 1034355111