Restructure Task class

[rhaschke]

Simplify Task class hierarchy. Currently, you distinguish between Task and TaskDesc. I suggest merging them, having finally the following members:

• name
• args (usually just reference (role of T_c) + goal (role of T_t) ?)
• argmap
• weight

These are updated during compute():

• J, lb, ub (for equality constraints lb == ub)
• softness = hard | linear | quadratic

These are updated during solve() and will allow for convergence check:

• residual
• violation
• importance (Lagrange multiplier)

[felixkol]

#9 implements everything but residual/violation and importance.
For both solvers residual/violation can be calculated easily.

Importance can only be calculated in the HQP solver (?). While iteration over the hierarchy, tasks occurring in later levels as null-space constraints will be assigned multiple importance values. How do we treat these?

[rhaschke]

Importance can only be calculated in the HQP solver (?).

Yes.

While iterating over the hierarchy, tasks occurring in later levels as null-space constraints will be assigned multiple importance values. How do we treat these?

I suggest keeping the first solution's values only.