Fixing bug where tiled editor supports decimals for object height but ntiled fails to parse it.
Added support for loading external tilesets (tsx files). It has been implemented as a pre-processor and manipulates
the XML document to minimise polluting the domain with file paths.
Merge remote-tracking branch 'patriksvensson/master'
Changed width to decimal since tiles supports it on both height and width.
Merge pull request #14 from naeemkhedarun/master

Patch for decimal heights (due to Tiled editor) and ability to load external tilesets.