support more engines

[sugizo]

objective support more engines both uci, xboard / winboard

already tested in osx by edit ~/Downloads/chs/lib/python*/site-packages/chs/engine/stockfish.py

1. tested engine path that work with popen_uci() and 'Skill level' active : uci : brainfish, fairy_stockfish, stockfish, stockfish_mv

2. tested engine path that work with popen_uci() and 'Skill level' inactive / commented : uci : asmfish, bikjump, brainfish, cinnamon, combusken, critter, deephiarcs, defenchess, drofa, ethereal, fairy_stockfish, fruit, gfruit, glaurung, hiarcs, komodo, laser, senpai, shredder_classic, smaug, stash, stockfish, stockfish_mv, tiny, toga2, wasp, winter, wyldchess, xiphos

uci_xboard : cheng, gnuchessu, greko, k2, sjaakii

3. tested engine path that work with popen_xboard() and 'Skill level' inactive / commented : uci_xboard : gaviota, greko, sjaakii

xboard : crafty, sjeng

the engines works can be more than tested above, perhaps due to python-chess module version updated, e.g. chessdblet, dreamer, fairymax, leonidas, phalanx, polyglot, pulsar, pychess, scidlet