Fixed #85: typo in docs mentioning item type 'dot' instead of 'range', and missing type 'rangeoverflow'
dont calculate gravity forces if constant is set to 0
Removed unnecessary zIndex
Merge remote-tracking branch 'origin/develop' into develop
Documented supported browsers.
bugfixes for IE9, style fixes
Merge branch 'develop' of https://github.com/almende/vis into develop
updated history
Released version 0.7.4
Bumped version number to v0.7.4-SNAPSHOT
Merge branch 'develop' into simplified

Conflicts:
	src/util.js
Moved the dots and vertical lines of box items to a separate panel