Ignore whitespace between indexed annotations

When creating uber jars via Maven Shade's AppendingTransformer, the
annotation indexes are concatenated, separated by line feed characters.

So let's just ingore whitespace between indexed annotations, handling the
illustrated problem gracefully.

This fixes https://github.com/scijava/scijava-common/issues/128.

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