IJ1 macro high-level convenience functions

[xulman]

There is a worry that users might not be able to convert their serial macros into a parallel one.
We might assume template situations (like "process all files in a folder", or "I want to run tasks from 10 till 68") and provide
dedicated functions for them, the functions are essentially only wrappers for the parallel for-cycle.

[velissarious]

I could add some of the functions I have written for the example scripts in the wrapper script for access in IJ1 Macro.

These functions could be used easily to split the iterations (workload) of any for-loop to the compute nodes.

However, these are implemented in Macro and would not be available in the case of Jython. It would not be possible to implement these in Java because of the limitations of the ImageJ call function. For example arrays can not be passed to Java though the call function.