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.
Merge branch 'master' into cache_tilesets
Merge branch 'remove_firstgid_from_tileset' into cache_tilesets

Conflicts:
	util/java/libtiled-java/src/tiled/io/TMXMapReader.java