Fixed ratio constraints.

cython/README.md

@@ -24,10 +24,10 @@ Build and install the module:
 python setup.py install
 ```
 
-Run unit test:
+Run unit tests:
 
 ```bash
-python tests
+python test
 ```
 
 Uninstall the module:

cython/python_solvespace/slvs.pyx

@@ -801,8 +801,7 @@ cdef class SolverSystem:
         if wp is _E_FREE_IN_3D:
             raise ValueError("this is a 2d constraint")
         if e1.is_line_2d() and e2.is_line_2d():
-            self.add_constraint(SLVS_C_EQ_PT_LN_DISTANCES, wp, value, _E_NONE,
-                                _E_NONE, e1, e2)
+            self.add_constraint(SLVS_C_LENGTH_RATIO, wp, value, _E_NONE, _E_NONE, e1, e2)
         else:
             raise TypeError(f"unsupported entities: {e1}, {e2}, {wp}")