Upgrade of presets to 1.5

This is the procedure to transform a pre-1.5 JavaCPP presets to a 1.5 presets, compatible with the Java Platform Module System. OpenCV and ffmpeg presets have already been upgraded to 1.5 and can be used as a model for upgrading other presets.

In the following <PS> is the name of the presets (e.g. ffmpeg) and <LIB> is the name of a native library (e.g. avcodec).

1. Delete and remove from repository all generated Java files located in <PS>/src/main/java/org/bytedeco/javacpp. Beware not to remove not-generated source files that may have been created in this directory. This can be safely done with a command like (using a unix shell):

cd <PS>/src/main/java/org/bytedeco/javacpp
git rm `grep -l 'DO NOT EDIT THIS FILE' *.java`

2. Rename the <PS>/src/main/java/org/bytedeco/javacpp directory to <PS>/src/main/java/org/bytedeco/<PS>, and adjust the packages and references in the helper and presets classes accordingly. A search&replace of org.bytedeco.javacpp.presets by org.bytedeco.<PS>.presets and org.bytedeco.javacpp.helper by org.bytedeco.<PS>.helper will do.
3. Create directory <PS>/src/java/org/bytedeco/<PS>/<LIB> for each native library. For presets with a single native library, you can skip this step.
4. Create directory <PS>/src/java/org/bytedeco/global
5. In the presets file <PS>/src/java/org/<PS>/presets/<LIB>.java: change the value of the target property to org.bytedeco.<PS>.<LIB>, or to org.bytedeco.<PS> if you skipped step 3. Add after the target property the new property global, with value org.bytedeco.<PS>.global.<LIB>. This is the name of the main class that will contain the global members of the library (not enclosed in a C++ class).
6. If some helper classes <PS>/src/main/java/org/bytedeco/helper/<LIB>.java contain static classes, move these classes out as standalone classes in the directory <PS>/src/main/java/org/bytedeco/<PS>/<LIB> (or <PS>/src/main/java/org/bytedeco/<PS> if you skipped step 3). Again, your IDE may help in such task by adapting the packages and changing references. Ensure these files are added to the repository.
7. Create <PS>/src/main/java9/module-info.java containing:

   module org.bytedeco.<PS> {
     requires transitive org.bytedeco.javacpp;
     exports org.bytedeco.<PS>.<LIB>;
   }

   Repeat the exports line for each native library included in the presets (or omit <LIB> if you skipped step 3). Also add any exported package that doesn't map a library, if such package exists. Add this file to the repository.
8. That's it. Give it a try with a mvn clean install -pl .,<PS>
9. If the build is successful, uncomment the lines related to the preset in the Travis config file /.travis.yml and AppVeyor config file /.appveyor.yml.
10. Add the generated sources to the repository: git add <PS>/src/gen.
11. Publish a PR.