checksysodesol method to check for solutions of system of odes

This PR contain checksysodesol method which checks for solutions given for system of ODEs. This also takes into account those equation where number of equation is not equal to number of functions as long as solutions for each functions is given.
Ok, I will change that to
```
if ss == 0:
    eq = 0
else:
    eq = ss.expand(force = True)
```