package/solarus: bump to version 1.6.0

package/solarus: bump to version 1.6.0

Here are the big features in Solarus 1.6:

    * OpenGL backend and support for GLSL shaders (by Stdgregwar and Vlag)
    * Support for external script editor of your choice.
        Zerobrane integration: autocompletion, debug breakpoints,
        stack inspection (by Stdgregwar)
    * Multiple improvements in map editor, including the much-requested
        contour generator, tile replacement and support for multiple
        tilesets
    * Multiple improvements in tileset editor, including multiple selection,
        custom frame count for animated tile patterns
    * Multiple improvements in sprite editor
    * Data import from other quests
    * Beautiful new free tilesets (Zoria by DragonDePlatino,
        Ocean’s Heart by Max Mraz)
    * Free pixel fonts (by Wekhter)
    * Custom hero states in Lua to allow advanced customization of the hero
    * Tons of new features in the Lua API

Last but not least: Solarus 1.6 is fully compatible with Solarus 1.5 quests.
You have no work to do to upgrade your project to Solarus 1.6.

Starting with version 1.6, the Solarus engine now require OpenGL (GLX) support.
The OpenGL ES support doesn't build, this issue has been reported upstream [1].

Update the download url since solarus no longer use github.
Rebase patch.

See:
http://www.solarus-games.org/2018/12/22/solarus-1-6-released

[1] https://gitlab.com/solarus-games/solarus/issues/1324

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>