v0.5.2

ConstraintSolver v0.5.2

Diff since v0.5.1

Closed issues:

• Speed up get_next_node (#194)
• Comparing x[1] <= x[i] throws BoundsError (#215)

Merged pull requests:

• use view_values for faster rm! (#214) (@Wikunia)
• check for x == x and x <= x constraints feasible and infeasible (#217) (@Wikunia)