[Xastir] Update Notice: OSM tile support changes

[Jerry Dunmire]

Hi,
I just committed code to CVS the does following:

    * fix for '1 of 0' tile download message
    * fixed a memory leak in map_OSM.c
    * fixed installation of OSM CC icons
    * added support for .jpg tiles
    * implemented transparency for tiles. No more red blocks for missing
      tiles, tiles can be stacked, and lower levels show through for
      missing tiles.
    * zoom level limits for OSM maps
    * New map definitions for topOSM

Try selecting the three new topOSM maps. Set the relief to level 0,
contours to level 1 and features to level 2. Note that the tiles are
only available for the west coast of the US. See http://toposm.com/.
My implementation in Xastir doesn't look as good as the web based
because of alpha blending issues.

Barring bugs, I'm going to move on from OSM tiles to see if I can
figure out the tiles from Terraserver.

Note that I have noticed some problems with the topOSM server,
including corrupt images and long timeouts when requesting a check for
'new than'. I found that deleting all of the topOSM tiles in
~/.xastir/OSMtiles/ 'solved' the problem. (OK, OK, solved is not
correct since I don't really know what is causing the problem.)

Good Mapping!

73,
...jerry
KA6HLD