Save memory by re-using empty TagInfo (and subclasses) arrays.

Arrays of TagInfo (and subclasses) often tend to be empty, as many
members simply won't have any of the relevant tags.
Re-using empty arrays saves potentially a dozen or more megabytes
for large projects.

Also some minor performance tweaks the Javadoc comment parsing.

Change-Id: Iffaddd3b59a4f8183f11efd6e2680aad95633ade
13 files changed