make estimate_mc (KS test) more user friendly

[aronsho]

Some issues that I encountered:

• the input requires a list of Mcs to test (mcs_test), and the function assumes that it is ordered
• mcs_test is also given back, but if stop_when_passed==True, then it might be longer than the list of p-values, making it harder to plot this
• What the user wants is most likely just the first mc that passes the test, but this has to be retrieved manually by checking the p-values

I propose the following changes:

• make the list of Mcs optional
• if a list is given, check that it is ordered
• make sure the output of the list of tested Mcs is the same length as the p-values and ks-distances
• adjust the output so one Mc (the first one that passes) is the first output (all other could be optional? adjust this with the output of the other mc functions)