weiss 0.8

Since v0.7 a month ago weiss has again gained over 100 self-play elo:

60+0.6
Score of weiss 0.8 vs weiss 0.7: +2184 -639 =1452
Elo difference: 131.50 +/- 8.79

Major changes in v0.8:

• Improved king PSQT #111
• Vastly improved aspiration window #117 #118 #119 #121
• Improved time management #125
• Vastly improved null move pruning #127 #128 #129 #130

And as usual lots of refactoring and cleanup.