Issue #2850 solved. Integration doesn't halt now.

In issue #2850 it was mentioned that ````integrate(asin(x)*log(x), x)````  does not give any answer. It just give ````Integral(log(x)*asin(x), x)```` which is probably wrong. The reason was ````asin and acos ```` was not implemented in ````manualintegrate.py````. It is now done.