Deal with various deprecation warnings in the code

[apocalyptech]

OpenBLCMM supports Java as far back as 8, still, but newer Java versions have various deprecation warnings which are popping up. Rather than wait until code starts actually breaking, I'll be doing some refactoring to get rid of the deprecation warnings for v1.4.0. (If possible, anyway -- if we run into something which is difficult or impossible to deal with while retaining Java 8 compatibility, we may have to rethink Java 8 support.)

The current ones fall into a couple of categories:

• URI(String) constructor
• InputEvent.getModifiers()
• InputEvent.CTRL_MASK
• ToolKit.getMenuShortcutKeyMask()
• JTextComponent.modelToView(int) and JTextComponent.viewToModel(Point)
• Runtime.exec(String)