0.8.0 release

Also needs uqm-content being upgraded to 0.8.0, as implemented in uqm-content!2 (closed)

  * New upstream release. (Closes: #640881 and #483637)
  * use SDL2 instead of SDL1
  * use .uqm files directly instead of unpacking them, as it makes
    Debian package more compatible with upstream and does not require
    problematic patches
  * update existing debian patches (and drop strings patch which is no
    longer needed since 0.7.0)
  * upgrade d/copyright to DEP5 (with more details for debian packaging)
  * upgrade d/watch and d/copyright to automatically create DFSG archive
    by removing doc/*
  * change versioning to recommended +dfsg instead of .dfsg
  * update to newer Standards-Version; Rules-Requires-Root in d/control
  * simplify CPU architecture detect for build
  * update desktop file entry to get rid of warnings
  * add autopkgtest