[Patch] Use java.util.Properties to read REVISION file in the Version-class

[floscher]

Previously the REVISION file was read from the resources using two custom methods in the Version-class: loadResourceFile(URL) and parseManifestStyleFormattedString(String)

I replaced those two with java.util.Properties.load(InputStream), which reduces the code in the Version-class.

As the method loadResourceFile(URL) was also used in the class AboutAction, I transferred it to that class, adapted it to better fit the needs of that class (don't produce an error when a resource file can't be read, but instead display a warning in the text area where normally the contents of that file would be displayed), renamed it to setTextFromResourceFile(JTextArea, String) and made it private.

[Don-vip]

In 9019/josm:

fix #12112 - Use java.util.Properties to read REVISION file in the Version-class (patch by floscher) + checkstyle