Merge pull request #632 from stefanbeller/master

Fix typo in travis
Add option to include background image when saving as image
Draw gray background when saving image if background is not valid
+ Added objects to the isometric (staggered) renderer
* Fixed bug that caused grey artifacts at the top left and right corners of a tall sprite when in isometric (staggered) renderer
add option to tmxrasterizer to include the layer named "collision"
fixed tabs vs spaces
Merge pull request #637 from sean-h/master

Add option to include background image when saving as image
Allow changing order of open document tabs
change command-line options to better control layer visibility
Match open document order with document tab order
make --hide-layer case-insensitive
Merge pull request #639 from gauauu/includeCollisions

Option to include collision layer in tmxrasterizer
Changed coding style to match the original
Added missing command line arguments to manpage
Fixed typo in help string of tmxrasterizer
Merge pull request #643 from Ablu/manpage_update

Manpage update
Change DocumentManager to use MovableTabWidget
Removed a non-functional hack that was causing a crash

This code was meant to make sure positions and sizes of objects stored
as part of tile collision information were in coordinates relative to
the tile texture, ranging from 0-1. However, it is no longer functional
since the map's tile width and height are no longer used by the map
reader and writer now that the objects store their positions in pixels
rather than tiles.

Overall I think it's anyway a better idea when the positions and sizes
are kept in pixels here and not stored in "texture coordinates", since
this is consistent with the units used in regular object groups. In
addition it is trivial to divide the values by the size of the tile to
obtain the texture coordinates.

Fixes #646
Fixed mapreader test

Object position and size are now stored in pixel instead of tile units.
Fixed staggeredrenderer test

Pixel coordinates were renamed to screen coordinates.