Solver for wild categories

[felixwellen]

It should be not too hard to write a solver for wild categories (might still be that I am missing some detail which causes a problem in the end...). I have the following scheme in mind, but there might be others:

• Construct the free wild category on a reflexive graph (partially done with Construct 'the' free wild category on a graph  #1117 )
• An equation between compositions of morphisms in a wild category is a (reflexive) diagram which is the boundary of a 2-cell.
• Use the universal property to construct a filler of this 2-cell if the compositions are equal in the free wild cat.
• Build a nice reflection interface.

Feel free to discuss this scheme and suggest improvements!