`solve_left` in M4RI is `solve_right` in sage

[cbouilla]

Indeed, what the mzd_solve_left() function does is exactly what is called M.solve_right() in sage.

It could be somewhat confusing, but I am not sure what is the best solution:

• Rename the function to mzd_solve_right() ?
• Add an alias for backward compatibility and stop advertising the old name ?
• Add run-time error if anyone calls the old function ?