Simplify command classes and examples

[emilmelnikov]

• Merge commands and executors for less indirection
• Move subprocess running, temporary file management and common parameters to the CommandBase class
• Simplify and merge together demo classes
• Add a simple pixel classification ImageJ macro

Partially supersedes https://github.com/ilastik/ilastik4ij/pull/84 without adding the features table feature.

[emilmelnikov]

This PR misses the Tracking demo because data files used in the old demo are not included in the project resources. This demo, along with other workflows, will be added later in another PR.

[k-dominik]

Okay I ran a few macros and they all still seem to work as before :+1:

[emilmelnikov]

Okay I ran a few macros and they all still seem to work as before 👍

Do you know how to read a "non-standard" (e.g. probabilities) image in a macro? For me it did not work because it needed to be imported via BioFormats that shows a pop-up dialog which doesn't work properly in the macro environment.

[emilmelnikov]

Do you know how to read a "non-standard" (e.g. probabilities) image in a macro? For me it did not work because it needed to be imported via BioFormats that shows a pop-up dialog which doesn't work properly in the macro environment.

After discussing this issue with @k-dominik, it turns out that some of our test TIFF files in this repo are not ImageJ-compatible. Re-exporting them with ImageJ should solve the problem.

[emilmelnikov]

Now everything that ilastik prints (both stdout and stderr) goes into the INFO log level. This prevents a log window from popping up when ilastik prints warnings to stderr, which is very common (it occurs if ilastik cannot find any solvers in the system).