cquad

Definitions

• discard means that the interval and it's children are not participating in the determination of the total integral anymore because it's parent did a refinement when the data of the interval wasn't known, and later it appeared that this interval had to split
• complete all the function values of the interval are known
• done the integral and the error for the interval has been calculated
• branch_complete the interval can be used to determine the total integral, (but if it's children are also branch_complete, they should be used.)

Closes #5 (closed).