Merge branch 'master' of 'scijava/annindex' into HEAD

SciJava-common makes use of annotations to be able to index classes to
provide a powerful plugin framework that allows for a flexible extension
mechanism by using annotation indexes generated at compile time, and
stored inside the artifacts.

SciJava-common used to rely on SezPoz for that, but we are switching to
our own, custom annotation indexer for the following reasons:

- we need better support for Eclipse (which does not run annotation
  processors in incremental compilation mode)

- we need a more robust data format (annotation indexes written out with
  SezPoz using an Oracle JDK cannot be read back using Android)

- since our main user -- the @Plugin annotation -- needs a RetentionPolicy
  of "runtime", there must not be a warning about that usage model

- SciJava-common's usage of the annotation index requires the latter to be
  handled carefully when it comes to class loader issues. While there has
  been a fix for SezPoz to that extent, donated by the SciJava project,
  the fix did not make it into a release for more than fourteen SciJava
  versions; SciJava has maintained its own SezPoz version for that reason.

To support the SciJava-related projects (including the ones uploaded to
ImageJ update sites where it cannot be guaranteed at all times that all
the uploaded artifacts were built with the newest SciJava common version),
the branch sports a backwards-compatible index reader that falls back to
SezPoz-generated indexes for artifacts that do not contain
SciJava-generated ones.

While at it, fill a few gaps in the pom.xml and bump the version to
2.6.0-SNAPSHOT (to reflect the new API)...

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Conflicts:
	.gitignore
	LICENSE.txt
	license/scijava/license.txt
	pom.xml
Add a main() method to the EclipseHelper

... so that it can be called easily... We will need this for
SciJava-common itself, in fact, because the annotation processor is now
part of that library, therefore it cannot be called while compiling
itself ;-)

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Ensure that SciJava-common's own annotations are indexed

... even if the tests are not run (which would trigger the
EclipseHelper)...

We still use SezPoz, but will switch in the next commit.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Switch to our own annotation indexer

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Stop using CheckSezPoz

We worked around SezPoz problems in conjunction with Eclipse' failure to
run annotation processors when required for a long time.

Based on what we learnt with CheckSezPoz, SciJava-common's very own
annotation indexer already implements the same functionality, rendering
the former obsolete.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Combine annotation indexes by simple concatenation

... now that they are written out as plain, concatenable JSON...

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Deprecate the SezPoz checker

We no longer need it; its functionality is implemented by the
EclipseHelper class now.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Do not depend on SezPoz any longer

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>