Bump the maximum tile margin and spacing in New Tileset dialog

The maximum was at 99 pixels and somebody was hitting that limit. The
main reason for the maximum is because QSpinBox determines its size
based on the maximum value. With the current layout, the maximum can be
9999 and it will still be the same size, because it's aligned to the
tile size spin box anyway which has that maximum already.

Closes #359
libtiled-java: Added zlib compression support to TMXMapWriter
libtiled-java: Do not output width and height for ObjectGroup

It's obsoleted.
libtiled-java: Do not store firstGid in each TileSet

Instead, they should be calculated on-the-fly when writing a TMX file.
Loading TMX files should parse the gids while the file is being loaded,
but not persist them inside the TileSet.
libtiled-java: Added support for caching tilesets

For example, when reusing the TMXMapReader to load several TMX files
that all have the same tileset definitions, the loader does not have to
load the tileset images several times, thus making the loading process
much faster.
Raised map size limits beyond all reason

Avoid crashing on map creation by not automatically creating a tile
layer when its size would exceed a gigabyte, and warning the user
about this fact.

Maps that only use object layers work fine at this size.
Added MapObject angle

* Added support for angle in TMX, Lua and JSON plugins
* Added support for angle drawing in orthogonal map renderer
* Added angle to Object Properties window
* Adapted MapObject bounding box (only rect shape and tile object) in
  orthogonal map renderer to contain the angle arrow
* Added a view option to enable or disable angle arrow
* Polygon/polyline don't have angle arrows

Conflicts-resolved-by: Thorbjørn Lindeijer

Conflicts:
	src/libtiled/mapobject.cpp
	src/libtiled/mapobject.h
	src/libtiled/mapreader.cpp
	src/libtiled/maprenderer.h
	src/libtiled/mapwriter.cpp
	src/tiled/mainwindow.cpp
	src/tiled/mainwindow.ui
	src/tiled/mapscene.cpp
	src/tiled/mapscene.h
	src/tiled/objectpropertiesdialog.ui
	src/tiled/preferences.cpp
	src/tiled/tiled.pro
Renamed object angle to object rotation
Added a 'snap to fine grid' feature

Allows for objects to be placed accurately at sub-tile increments.
Added a rotation handle to the map object item

The item is now rotated rather than just showing an arrow.

There are still some problems with this:

* Edit polygon tool does not cope with it
* Would feel less weird when objects rotated around their center
* This makes no sense for non-tile objects on isometric maps

Closes #11  (support for rotating objects)
Closes #325 (rotate object image)

Sponsored-by: Ben Wales
Removed the option to show rotation arrows

If they are to be drawn, it should be done by the map object item and
not by each map renderer. For now I'm just removing it since it doesn't
seem that helpful to me anyway when the objects are already rotated
themselves.
Allow objects to be flipped horizontally and vertically

Flipping is supported for tile objects and polygons, and for both
orthogonal maps and isometric maps.

Flipping currently does not take into account object rotation,
so "horizontal" flipping might mean something else for rotated objects.
Also, when flipping groups of objects, they are flipped individually.
These issues can be resolved later.

Closes #58  (flipping for tile objects)
Closes #116 (applying tile offset to tile objects)
Closes #154 (flipping for polygons and polylines)

Sponsored-by: Ben Wales
Apply flip and rotate shortcuts to selected objects

When applicable, the X and Y shortcuts will now flip selected objects
and the Z and Shift+Z shortcuts will rotate them.
Handle object rotation in Edit Polygon Tool
Merge branch 'wip/rotation'
Fixed compile against Qt 5

A parameter was dropped from QCoreApplication::translate.
Avoid using Windows 95 style

The Windows 95 style is really ugly but somehow gets chosen by default
sometimes, even with Qt 5 where the much better Fusion style is available.
Avoid it on any platform but Windows.

The code was borrowed from Qt Creator.
Allow cross-compiling Tiled using MinGW

Needed some small modifications.
Merge branch '0.9'
Change tileset image source in UI

This closes #331.