Add option to include background image when saving as image
Draw gray background when saving image if background is not valid
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
change command-line options to better control layer visibility
make --hide-layer case-insensitive
Merge pull request #639 from gauauu/includeCollisions

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

Manpage update
tile layer: added horizontal and vertical offset properties
map reader: read horizontal and vertical offset for tile layers
map writer: write horizontal and vertical offset for tile layers
property browser: added horizontal and vertical offsets for tile layers
isometric renderer: first take at rendering offseted layers
map renderer: added method to calculate the max offsets from all the layers
isometric renderer: use the max layers offsets to correctly calculate the map size
map: moved the logic to calculate offsets to the map instead of the renderer
layermodel: recalculate map offset on layer offset change