Add bearing information while creating route/track

Add more information in status bar while creating route or track.
These informations are:
- bearing
- step distance

Signed-off-by: Guilhem Bonnefille <guilhem.bonnefille@gmail.com>
Fix screenshot included in previous commit
Allow an acquire datasource method to *not* have to use a threading mechanism.

Restructure acquire thread usage to enable commonalities for the non thread method to work.
Allow downloading with authentication via curl

New DownloadMapOption to specify the username and password as a single string of the format 'username:password'
Allow acquiring an URL with a username/password authenticated download.

Have to extend the parameters in the datasource method to pass around download options.
Store the main thread value so comparisons can be made to determine the gdk update method
Fix: Improve internal redrawing method for layer panel updates.

Remove hopefully the last place where updating the display is performed from a background thread
Use the thread value to see if it's the main thread or not and then
use the appropriate gtk idle drawing methods for the layers_panel update.
Simplify layer update redraw in determining the gtk update method.

Use the thread value itself to determine whether it's from the main thread or not.
Move 'Add Wikipedia Waypoints' into the Acquire Menu in the TrackWaypoint Layer.

Relabel and reassign accelerators as necessary.
Remove useless 'selected' check box on Wikipedia points creation method.

The list itself is multi-selectable and is now enabled to determine what should be created.
This has many advantages such as:
. Being able to click anywhere on line to select it
. Using Ctrl+A to select everything.
Save Wikipedia Waypoint links in a simple format as the waypoint comment.

This allows the link to be opened within Viking via the recent change in:
commit SHA1:7f2742755c3243d3ddd58692998a658a89b4adcf
Simplify getting bounds for wikipedia waypoints by reusing existing function.
Fix geonames country pattern
Add getting Wikipedia Waypoints via the File->Acquire menu method.

Auto creates a TrackWaypoint layer.
Decide the 'feature' type is more useful than seeing the country code.
Allow the columns to be sortable in the Wikipedia Waypoints that are available.

Make sure selected items are the correct references to stored items.
All translated versions to select appropriate language Wikipedia articles.
Allow for getting more Wikipedia Waypoints (up to 20).

Make the dialog scrollable to view longer lists.

One day might make this value configurable somewhere.
Use elevation values in creating waypoints from Wikipedia.
Use Wikipedia featue type to generate a suitable waypoint icon