Changed the dtype of 'b' array to from int8 to uint8.

Also use uint8_t for the 'bin' index variable instead of char.

This fixes a segfault when the values in 'b' array are larger then 127
and the platform char is an signed type.
Fixed a use before initialization error.
Rebuild 'contingency.c' files.
Merge pull request #5 from ales-erjavec/bottlechest

Bug fix in contingency function