Avoid requiring Java 1.6 even on modern MacOSX versions

[dscho]

On modern MacOSX versions (10.8 and newer), newer Java versions are available. However, due to our linking to the JavaVM framework – in which form Java is no longer provided – MacOSX asks the user to download Java 1.6, even if a --java-home argument is passed.

Let's switch to the dlopen() method instead which avoids downloading Java 1.6, and let's also default to the newest Java that is installed by the user (or administrator).

[dscho]

@fjug you owe me a beer ;-)

[fjug]

Yeah! Awesome!

On 26 Jan 2015, at 02:22, dscho notifications@github.com wrote:

@fjug https://github.com/fjug you owe me a beer ;-)

— Reply to this email directly or view it on GitHub https://github.com/imagej/imagej-launcher/pull/25#issuecomment-71404342.

[ctrueden]

As discussed in person, this change will need testing on a variety of OS X machines across the spectrum of what's out there, before we start shipping it. So I will send a mail to the ImageJ users list cajoling OS X users to test it. We especially need to know:

• Does it work on various OS X versions which have not installed any Javas at all?
• Does it work on an OS X machine that has never had a copy of Java 6 on it? I.e., a newer version of OS X, where the user just installed Java 8 and nothing more?

We expect that the former case might be a problem on newer machines with no Java installed, but we can improve the launcher further later to detect this situation and recommend to install Java in a pop-up dialog (but not by linking to the framework, which suggests to install the obsolete Java 6).