[Tracker] [PATCH] Moving towards internal metadata extractors

["Edward Duffy" <eduffy gmail com>]

Here's a patch for src/trackerd/tracker-metadata.c that can use
internal metadata extractors, depending on mimetype.  If no internal
extractor is provided, it falls back to the old method using
tracker-extract.  I've included extractors for Oasis (Open Office
files), postscript, and AbiWord.  I'm looking at the PDF parser in
libextractor's repos, and will hopefully have a patch for that soon.

So far, this is just extraction, no metadata replacement.

The interface is a little different than the one proposed by Jamie the
other day:

void tracker_metadata_extract_oasis (gchar *, GHashTable *);

The metadata hashtable is a parameter instead of creating a new one
and returning it.