Extend CONTRIBUTING.md and adapt some Eclipse project settings to simplify getting started

[travkin79]

This PR

• explains in more details how to start contributing, e.g. how to import Eclipse projects and how to launch the plug-ins
• adds .project files and Eclipse settings to simplify Eclipse project import for new developers
• Explains how to configure the Checkstyle Eclipse plug-in to work with this git repo

[travkin79]

Hello @jdneo,
I have some suggestions how to simplify the first steps for new contributors. Could you please take a look at this PR? Do the suggestions make sense for you? Is it ok to have them in one single PR?

Besides, I had some questions left:

• Which of the two target definition files are you usually using for development? I took target-tm-terminal.target
• It seems, the launch config launch/plugin_debug_configuration.launch is not up-to-date or incomplete. For example, I didn't see any agent bundles selected. Are you usually using some other launch config? I guess, there should be different launch configs, one for each OS or one config explicitly for a particular OS.

[jdneo]

Thank you, sorry for the confusion we have. I guess we do have some gaps here for the contribution.

Which of the two target definition files are you usually using for development? I took target-tm-terminal.target

This is a good point. TBH, I usually just using the running platform to makes sure the launched debug session is similar to a real eclipse instance. But when it comes to debug a test case, I will switch to target-terminal.target because I use a newer Eclipse version. (There is a bundle namespace change between old eclipse and new eclipse for the terminal bundle, that's why we have two of them.)

But I admit that this setup is wired, I'm just not able to find some time organize them systematically.

It seems, the launch config launch/plugin_debug_configuration.launch is not up-to-date or incomplete. For example, I didn't see any agent bundles selected. Are you usually using some other launch config? I guess, there should be different launch configs, one for each OS or one config explicitly for a particular OS.

Because I usually use running platform as the target platform, so when I launch a debug session, I enabled all the plugins. Maybe this is not the best practice? Any suggestions?