New plugin features to support JavaFX 11

[Don-vip]

With the removal of JavaFX in Java 11 (#16047), the following features won't work anymore by default:

• core: MP3 support
• plugin StreetSide
• plugin matsim

I don't want to include openjfx directly in JOSM core just for MP3 support. A better way could be to include it in a plugin on which streetside and matsim plugin can depend.

Problems to resolve:

• JavaFX is based on native libraries, the plugin must install only those for the current platform. If I remember correctly the JOGL plugin does already something like this.
• the plugin classes will have to be made available to JOSM core classloader for MP3 support => a new plugin property must be added for this (Core-Export?) => The package org.openstreetmap.josm.io.audio.fx will have to move to this new plugin
• the plugin will include OpenJFX 11. As we still need to support Java 8, the plugin must not be loaded on Java <= 10, for compatibility reasons => a new plugin property must be added for this (Minimum-Java-Version?)

[stoecker]

the plugin classes will have to be made available to JOSM core classloader for MP3 support => a new plugin property must be added for this (Core-Export?)

Why can't the plugin provide the related functionality instead of providing required base classes (like the input file support)? That approach sounds strange.

[stoecker]

Change proposed name

[Don-vip]

Replying to stoecker:

the plugin classes will have to be made available to JOSM core classloader for MP3 support => a new plugin property must be added for this (Core-Export?)

Why can't the plugin provide the related functionality instead of providing required base classes (like the input file support)? That approach sounds strange.

Yes, it's a simpler, safer and more elegant solution. Thanks.