holy diff batman!

That way we can search through all logs in constant time instead of having to perform a full table scan.

Those variables were confusing because autoconf usually defines DATADIR to
PREFIX/share and gajim uses both defs.datadir=PREFIX/share/gajim and
gajim.DATA_DIR=PREFIX/share/gajim/data.

Now, autoconf will use PKGDATADIR for setting the (renamed) defs.basedir
variable which will be used to set gajimpaths['DATA_DIR'] and
gajimpaths['ICONS_DIR'] in configpaths.py

Gajim will also looks for the ${GAJIM_BASEDIR} environment variable instead of
${datadir} which was really too generic (no namespace).

Thanks Asterix for the initial version of this patch!

show only once unread messages at startup when we have twice the same contact in 2 accounts. Fixes #2921

* we now handle roster push and roster reception
* changed version number in src/common/defs.py

 * remove js from some headers
 * set coding:utf-8 to allow real names in headers

 * Remove some licencing problems
 * To do: same for images
 * See #4200

we have that in all files. To at least lesser the confusion a bit, add
vim tags for that.
Additionally, fix wrong #! in a few files.

when the defs.py file is changed.