Used sqrt() instead of ln() for casting, should be faster

More precise direction detecting, prevented many abundant calculations(also involved a magic number), and make collapsing converge quicker

The breaking dust size is relative to the break size now

Fixed a bug that mass calculation is using shape handle instead of real mass

Improved breaking pattern

Completely rewritten, with new calculation methods.

Static objects will collapse only when:

Have body detached from it
The body has moved away(out of range)
Has enough mass

These combined will cause some nice chain collapsing.