Make EventHandlers consistently private

While at it, add Javadoc for the parameter to suppress Eclipse's
warnings reliably (i.e. independent of the users' settings which might
warn about unused parameters, or alternatively -- and annoyingly --
about superfluous @SuppressWarning("unused")!).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Use ModuleIdentifier#getIdentifier() for legacy-compatible things

This developer missed the getIdentifier() method and crafted (pretty
similar-looking) identifiers. Let's use the real thing instead.

Pointed out by Curtis Rueden.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Sort legacy-compatible menu items

This imposes a consistent order: menu weight first, alphabetically
second sort key. That way, it no longer matters in which order the
file system reports the files (which is different between machines).

The issue was reported out by Christophe Leterrier.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Add separators before legacy-compatible menu items

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Merge pull request #62 from imagej/consistent-menu-order

Add legacy-compatible commands and scripts to the menu structure in a consistent order