weiss 0.6

Since v0.5 a month ago weiss has gained about 300 elo.

Score of weiss 0.6 vs weiss 0.5: +318 -23 =59 [0.869]
Elo difference: 328.32 +/- 41.94

Major changes in v0.6:

• Tapered evaluation #52
• (Very simple) king safety #61
• Lazy movegen (gen quiets only if necessary) #67
• Late move reduction #70 #71 #76
• Mobility added to eval #79 #80 #81 #82
• Avoids dropping into quiescence while in check #83

Along with many minor improvements to values, code cleanup / refactoring etc.

BUG: weiss incorrectly states its version is 0.5. I just forgot to update it, it is 0.6.