Merge branch 'release-0.1.2' into develop
add a kind accessor in Object
add a TileObject (with a gid) and removes gid from other objects
make a new version of tmx_render with Qt5 instead of SFML2
do not render not orthogonal maps
add various utility methods
show images defined in objects
use the size of the image if declared in the TMX file
put geometric structures in their own header
bump version to 0.2.0
add a ChangeLog and a CONTRIBUTING file
change the copyright date
Merge branch 'release-0.2.0'