Documentation: difference rerun, runall #203

In the package documentation Section 4.1 it seems as if there is a slight difference between rerun=always and runall=true.
At least the formulations are different.
I found out that the pytxcode file stores rerun only, and pythontex command line tool cannot even read runall.
I did not check details but one seems obsolete.
In the commandline tool, the according options cannot be specified both.
Maybe it is a good idea to do so also in the package option.

Since it is the pytxcode file which passes information to pythontex tool,
the and the pacakge options runall=true/false is converted into rerun=always/default , pythontex cannot distinguish the two.